class Sequel::Dataset

A dataset represents an SQL query. Datasets can be used to select, insert, update and delete records.

Query results are always retrieved on demand, so a dataset can be kept around and reused indefinitely (datasets never cache results):

my_posts = DB[:posts].where(author: 'david') # no records are retrieved
my_posts.all # records are retrieved
my_posts.all # records are retrieved again

Datasets are frozen and use a functional style where modification methods return modified copies of the the dataset. This allows you to reuse datasets:

posts = DB[:posts]
davids_posts = posts.where(author: 'david')
old_posts = posts.where{stamp < Date.today - 7}
davids_old_posts = davids_posts.where{stamp < Date.today - 7}

Datasets are Enumerable objects, so they can be manipulated using many of the Enumerable methods, such as map and inject. Note that there are some methods that Dataset defines that override methods defined in Enumerable and result in different behavior, such as select and group_by.

For more information, see the “Dataset Basics” guide.

Constants

OPTS
TRUE_FREEZE

Whether Dataset#freeze can actually freeze datasets. True only on ruby 2.4+, as it requires clone(freeze: false)

1 - Methods that return modified datasets

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Constants

COLUMN_CHANGE_OPTS

The dataset options that require the removal of cached columns if changed.

CONDITIONED_JOIN_TYPES

These symbols have _join methods created (e.g. inner_join) that call join_table with the symbol, passing along the arguments and block from the method call.

EMPTY_ARRAY
EXTENSIONS

Hash of extension name symbols to callable objects to load the extension into the Dataset object (usually by extending it with a module defined in the extension).

JOIN_METHODS

All methods that return modified datasets with a joined table added.

NON_SQL_OPTIONS

Which options don't affect the SQL generation. Used by simple_select_all? to determine if this is a simple SELECT * FROM table.

QUERY_METHODS

Methods that return modified datasets

SIMPLE_SELECT_ALL_ALLOWED_FROM

From types allowed to be considered a simple_select_all

UNCONDITIONED_JOIN_TYPES

These symbols have _join methods created (e.g. natural_join). They accept a table argument and options hash which is passed to join_table, and they raise an error if called with a block.

Public Class Methods

register_extension(ext, mod=nil, &block) click to toggle source

Register an extension callback for Dataset objects. ext should be the extension name symbol, and mod should either be a Module that the dataset is extended with, or a callable object called with the database object. If mod is not provided, a block can be provided and is treated as the mod object.

If mod is a module, this also registers a Database extension that will extend all of the database's datasets.

   # File lib/sequel/dataset/query.rb
55 def self.register_extension(ext, mod=nil, &block)
56   if mod
57     raise(Error, "cannot provide both mod and block to Dataset.register_extension") if block
58     if mod.is_a?(Module)
59       block = proc{|ds| ds.extend(mod)}
60       Sequel::Database.register_extension(ext){|db| db.extend_datasets(mod)}
61     else
62       block = mod
63     end
64   end
65   Sequel.synchronize{EXTENSIONS[ext] = block}
66 end

Public Instance Methods

_clone(opts = nil || (return self))

Save original clone implementation, as some other methods need to call it internally.

Alias for: clone
clone(opts = nil || (return self)) click to toggle source

Returns a new clone of the dataset with the given options merged. If the options changed include options in COLUMN_CHANGE_OPTS, the cached columns are deleted. This method should generally not be called directly by user code.

Calls superclass method
   # File lib/sequel/dataset/query.rb
84 def clone(opts = nil || (return self))
85   # return self used above because clone is called by almost all
86   # other query methods, and it is the fastest approach
87   c = super(:freeze=>false)
88   c.opts.merge!(opts)
89   unless opts.each_key{|o| break if COLUMN_CHANGE_OPTS.include?(o)}
90     c.clear_columns_cache
91   end
92   c.freeze
93 end
Also aliased as: _clone
distinct(*args, &block) click to toggle source

Returns a copy of the dataset with the SQL DISTINCT clause. The DISTINCT clause is used to remove duplicate rows from the output. If arguments are provided, uses a DISTINCT ON clause, in which case it will only be distinct on those columns, instead of all returned columns. If a block is given, it is treated as a virtual row block, similar to where. Raises an error if arguments are given and DISTINCT ON is not supported.

DB[:items].distinct # SQL: SELECT DISTINCT * FROM items
DB[:items].order(:id).distinct(:id) # SQL: SELECT DISTINCT ON (id) * FROM items ORDER BY id
DB[:items].order(:id).distinct{func(:id)} # SQL: SELECT DISTINCT ON (func(id)) * FROM items ORDER BY id

There is support for emualting the DISTINCT ON support in MySQL, but it does not support the ORDER of the dataset, and also doesn't work in many cases if the ONLY_FULL_GROUP_BY sql_mode is used, which is the default on MySQL 5.7.5+.

    # File lib/sequel/dataset/query.rb
123 def distinct(*args, &block)
124   virtual_row_columns(args, block)
125   if args.empty?
126     cached_dataset(:_distinct_ds){clone(:distinct => EMPTY_ARRAY)}
127   else
128     raise(InvalidOperation, "DISTINCT ON not supported") unless supports_distinct_on?
129     clone(:distinct => args.freeze)
130   end
131 end
except(dataset, opts=OPTS) click to toggle source

Adds an EXCEPT clause using a second dataset object. An EXCEPT compound dataset returns all rows in the current dataset that are not in the given dataset. Raises an InvalidOperation if the operation is not supported. Options:

:alias

Use the given value as the from_self alias

:all

Set to true to use EXCEPT ALL instead of EXCEPT, so duplicate rows can occur

:from_self

Set to false to not wrap the returned dataset in a from_self, use with care.

DB[:items].except(DB[:other_items])
# SELECT * FROM (SELECT * FROM items EXCEPT SELECT * FROM other_items) AS t1

DB[:items].except(DB[:other_items], all: true, from_self: false)
# SELECT * FROM items EXCEPT ALL SELECT * FROM other_items

DB[:items].except(DB[:other_items], alias: :i)
# SELECT * FROM (SELECT * FROM items EXCEPT SELECT * FROM other_items) AS i
    # File lib/sequel/dataset/query.rb
150 def except(dataset, opts=OPTS)
151   raise(InvalidOperation, "EXCEPT not supported") unless supports_intersect_except?
152   raise(InvalidOperation, "EXCEPT ALL not supported") if opts[:all] && !supports_intersect_except_all?
153   compound_clone(:except, dataset, opts)
154 end
exclude(*cond, &block) click to toggle source

Performs the inverse of Dataset#where. Note that if you have multiple filter conditions, this is not the same as a negation of all conditions.

DB[:items].exclude(category: 'software')
# SELECT * FROM items WHERE (category != 'software')

DB[:items].exclude(category: 'software', id: 3)
# SELECT * FROM items WHERE ((category != 'software') OR (id != 3))

Also note that SQL uses 3-valued boolean logic (true, false, NULL), so the inverse of a true condition is a false condition, and will still not match rows that were NULL originally. If you take the earlier example:

DB[:items].exclude(category: 'software')
# SELECT * FROM items WHERE (category != 'software')

Note that this does not match rows where category is NULL. This is because NULL is an unknown value, and you do not know whether or not the NULL category is software. You can explicitly specify how to handle NULL values if you want:

DB[:items].exclude(Sequel.~(category: nil) & {category: 'software'})
# SELECT * FROM items WHERE ((category IS NULL) OR (category != 'software'))
    # File lib/sequel/dataset/query.rb
180 def exclude(*cond, &block)
181   add_filter(:where, cond, true, &block)
182 end
exclude_having(*cond, &block) click to toggle source

Inverts the given conditions and adds them to the HAVING clause.

DB[:items].select_group(:name).exclude_having{count(name) < 2}
# SELECT name FROM items GROUP BY name HAVING (count(name) >= 2)

See documentation for exclude for how inversion is handled in regards to SQL 3-valued boolean logic.

    # File lib/sequel/dataset/query.rb
191 def exclude_having(*cond, &block)
192   add_filter(:having, cond, true, &block)
193 end
extension(*a) click to toggle source

Return a clone of the dataset loaded with the given dataset extensions. If no related extension file exists or the extension does not have specific support for Dataset objects, an Error will be raised.

    # File lib/sequel/dataset/query.rb
199 def extension(*a)
200   c = _clone(:freeze=>false)
201   c.send(:_extension!, a)
202   c.freeze
203 end
filter(*cond, &block) click to toggle source

Alias for where.

    # File lib/sequel/dataset/query.rb
215 def filter(*cond, &block)
216   where(*cond, &block)
217 end
for_update() click to toggle source

Returns a cloned dataset with a :update lock style.

DB[:table].for_update # SELECT * FROM table FOR UPDATE
    # File lib/sequel/dataset/query.rb
222 def for_update
223   cached_dataset(:_for_update_ds){lock_style(:update)}
224 end
from(*source, &block) click to toggle source

Returns a copy of the dataset with the source changed. If no source is given, removes all tables. If multiple sources are given, it is the same as using a CROSS JOIN (cartesian product) between all tables. If a block is given, it is treated as a virtual row block, similar to where.

DB[:items].from # SQL: SELECT *
DB[:items].from(:blah) # SQL: SELECT * FROM blah
DB[:items].from(:blah, :foo) # SQL: SELECT * FROM blah, foo
DB[:items].from{fun(arg)} # SQL: SELECT * FROM fun(arg)
    # File lib/sequel/dataset/query.rb
235 def from(*source, &block)
236   virtual_row_columns(source, block)
237   table_alias_num = 0
238   ctes = nil
239   source.map! do |s|
240     case s
241     when Dataset
242       if hoist_cte?(s)
243         ctes ||= []
244         ctes += s.opts[:with]
245         s = s.clone(:with=>nil)
246       end
247       SQL::AliasedExpression.new(s, dataset_alias(table_alias_num+=1))
248     when Symbol
249       sch, table, aliaz = split_symbol(s)
250       if aliaz
251         s = sch ? SQL::QualifiedIdentifier.new(sch, table) : SQL::Identifier.new(table)
252         SQL::AliasedExpression.new(s, aliaz.to_sym)
253       else
254         s
255       end
256     else
257       s
258     end
259   end
260   o = {:from=>source.empty? ? nil : source.freeze}
261   o[:with] = ((opts[:with] || EMPTY_ARRAY) + ctes).freeze if ctes
262   o[:num_dataset_sources] = table_alias_num if table_alias_num > 0
263   clone(o)
264 end
from_self(opts=OPTS) click to toggle source

Returns a dataset selecting from the current dataset. Options:

:alias

Controls the alias of the table

:column_aliases

Also aliases columns, using derived column lists. Only used in conjunction with :alias.

ds = DB[:items].order(:name).select(:id, :name)
# SELECT id,name FROM items ORDER BY name

ds.from_self
# SELECT * FROM (SELECT id, name FROM items ORDER BY name) AS t1

ds.from_self(alias: :foo)
# SELECT * FROM (SELECT id, name FROM items ORDER BY name) AS foo

ds.from_self(alias: :foo, column_aliases: [:c1, :c2])
# SELECT * FROM (SELECT id, name FROM items ORDER BY name) AS foo(c1, c2)
    # File lib/sequel/dataset/query.rb
283 def from_self(opts=OPTS)
284   fs = {}
285   @opts.keys.each{|k| fs[k] = nil unless non_sql_option?(k)}
286   pr = proc do
287     c = clone(fs).from(opts[:alias] ? as(opts[:alias], opts[:column_aliases]) : self)
288     if cols = _columns
289       c.send(:columns=, cols)
290     end
291     c
292   end
293 
294   opts.empty? ? cached_dataset(:_from_self_ds, &pr) : pr.call
295 end
grep(columns, patterns, opts=OPTS) click to toggle source

Match any of the columns to any of the patterns. The terms can be strings (which use LIKE) or regular expressions if the database supports that. Note that the total number of pattern matches will be Array(columns).length * Array(terms).length, which could cause performance issues.

Options (all are boolean):

:all_columns

All columns must be matched to any of the given patterns.

:all_patterns

All patterns must match at least one of the columns.

:case_insensitive

Use a case insensitive pattern match (the default is case sensitive if the database supports it).

If both :all_columns and :all_patterns are true, all columns must match all patterns.

Examples:

dataset.grep(:a, '%test%')
# SELECT * FROM items WHERE (a LIKE '%test%' ESCAPE '\')

dataset.grep([:a, :b], %w'%test% foo')
# SELECT * FROM items WHERE ((a LIKE '%test%' ESCAPE '\') OR (a LIKE 'foo' ESCAPE '\')
#   OR (b LIKE '%test%' ESCAPE '\') OR (b LIKE 'foo' ESCAPE '\'))

dataset.grep([:a, :b], %w'%foo% %bar%', all_patterns: true)
# SELECT * FROM a WHERE (((a LIKE '%foo%' ESCAPE '\') OR (b LIKE '%foo%' ESCAPE '\'))
#   AND ((a LIKE '%bar%' ESCAPE '\') OR (b LIKE '%bar%' ESCAPE '\')))

dataset.grep([:a, :b], %w'%foo% %bar%', all_columns: true)
# SELECT * FROM a WHERE (((a LIKE '%foo%' ESCAPE '\') OR (a LIKE '%bar%' ESCAPE '\'))
#   AND ((b LIKE '%foo%' ESCAPE '\') OR (b LIKE '%bar%' ESCAPE '\')))

dataset.grep([:a, :b], %w'%foo% %bar%', all_patterns: true, all_columns: true)
# SELECT * FROM a WHERE ((a LIKE '%foo%' ESCAPE '\') AND (b LIKE '%foo%' ESCAPE '\')
#   AND (a LIKE '%bar%' ESCAPE '\') AND (b LIKE '%bar%' ESCAPE '\'))
    # File lib/sequel/dataset/query.rb
332 def grep(columns, patterns, opts=OPTS)
333   column_op = opts[:all_columns] ? :AND : :OR
334   if opts[:all_patterns]
335     conds = Array(patterns).map do |pat|
336       SQL::BooleanExpression.new(column_op, *Array(columns).map{|c| SQL::StringExpression.like(c, pat, opts)})
337     end
338     where(SQL::BooleanExpression.new(:AND, *conds))
339   else
340     conds = Array(columns).map do |c|
341       SQL::BooleanExpression.new(:OR, *Array(patterns).map{|pat| SQL::StringExpression.like(c, pat, opts)})
342     end
343     where(SQL::BooleanExpression.new(column_op, *conds))
344   end
345 end
group(*columns, &block) click to toggle source

Returns a copy of the dataset with the results grouped by the value of the given columns. If a block is given, it is treated as a virtual row block, similar to where.

DB[:items].group(:id) # SELECT * FROM items GROUP BY id
DB[:items].group(:id, :name) # SELECT * FROM items GROUP BY id, name
DB[:items].group{[a, sum(b)]} # SELECT * FROM items GROUP BY a, sum(b)
    # File lib/sequel/dataset/query.rb
354 def group(*columns, &block)
355   virtual_row_columns(columns, block)
356   clone(:group => (columns.compact.empty? ? nil : columns.freeze))
357 end
group_and_count(*columns, &block) click to toggle source

Returns a dataset grouped by the given column with count by group. Column aliases may be supplied, and will be included in the select clause. If a block is given, it is treated as a virtual row block, similar to where.

Examples:

DB[:items].group_and_count(:name).all
# SELECT name, count(*) AS count FROM items GROUP BY name
# => [{:name=>'a', :count=>1}, ...]

DB[:items].group_and_count(:first_name, :last_name).all
# SELECT first_name, last_name, count(*) AS count FROM items GROUP BY first_name, last_name
# => [{:first_name=>'a', :last_name=>'b', :count=>1}, ...]

DB[:items].group_and_count(Sequel[:first_name].as(:name)).all
# SELECT first_name AS name, count(*) AS count FROM items GROUP BY first_name
# => [{:name=>'a', :count=>1}, ...]

DB[:items].group_and_count{substr(:first_name, 1, 1).as(:initial)}.all
# SELECT substr(first_name, 1, 1) AS initial, count(*) AS count FROM items GROUP BY substr(first_name, 1, 1)
# => [{:initial=>'a', :count=>1}, ...]
    # File lib/sequel/dataset/query.rb
385 def group_and_count(*columns, &block)
386   select_group(*columns, &block).select_append(COUNT_OF_ALL_AS_COUNT)
387 end
group_append(*columns, &block) click to toggle source

Returns a copy of the dataset with the given columns added to the list of existing columns to group on. If no existing columns are present this method simply sets the columns as the initial ones to group on.

DB[:items].group_append(:b) # SELECT * FROM items GROUP BY b
DB[:items].group(:a).group_append(:b) # SELECT * FROM items GROUP BY a, b
    # File lib/sequel/dataset/query.rb
395 def group_append(*columns, &block)
396   columns = @opts[:group] + columns if @opts[:group]
397   group(*columns, &block)
398 end
group_by(*columns, &block) click to toggle source

Alias of group

    # File lib/sequel/dataset/query.rb
360 def group_by(*columns, &block)
361   group(*columns, &block)
362 end
group_cube() click to toggle source

Adds the appropriate CUBE syntax to GROUP BY.

    # File lib/sequel/dataset/query.rb
401 def group_cube
402   raise Error, "GROUP BY CUBE not supported on #{db.database_type}" unless supports_group_cube?
403   clone(:group_options=>:cube)
404 end
group_rollup() click to toggle source

Adds the appropriate ROLLUP syntax to GROUP BY.

    # File lib/sequel/dataset/query.rb
407 def group_rollup
408   raise Error, "GROUP BY ROLLUP not supported on #{db.database_type}" unless supports_group_rollup?
409   clone(:group_options=>:rollup)
410 end
grouping_sets() click to toggle source

Adds the appropriate GROUPING SETS syntax to GROUP BY.

    # File lib/sequel/dataset/query.rb
413 def grouping_sets
414   raise Error, "GROUP BY GROUPING SETS not supported on #{db.database_type}" unless supports_grouping_sets?
415   clone(:group_options=>:"grouping sets")
416 end
having(*cond, &block) click to toggle source

Returns a copy of the dataset with the HAVING conditions changed. See where for argument types.

DB[:items].group(:sum).having(sum: 10)
# SELECT * FROM items GROUP BY sum HAVING (sum = 10)
    # File lib/sequel/dataset/query.rb
422 def having(*cond, &block)
423   add_filter(:having, cond, &block)
424 end
intersect(dataset, opts=OPTS) click to toggle source

Adds an INTERSECT clause using a second dataset object. An INTERSECT compound dataset returns all rows in both the current dataset and the given dataset. Raises an InvalidOperation if the operation is not supported. Options:

:alias

Use the given value as the from_self alias

:all

Set to true to use INTERSECT ALL instead of INTERSECT, so duplicate rows can occur

:from_self

Set to false to not wrap the returned dataset in a from_self, use with care.

DB[:items].intersect(DB[:other_items])
# SELECT * FROM (SELECT * FROM items INTERSECT SELECT * FROM other_items) AS t1

DB[:items].intersect(DB[:other_items], all: true, from_self: false)
# SELECT * FROM items INTERSECT ALL SELECT * FROM other_items

DB[:items].intersect(DB[:other_items], alias: :i)
# SELECT * FROM (SELECT * FROM items INTERSECT SELECT * FROM other_items) AS i
    # File lib/sequel/dataset/query.rb
443 def intersect(dataset, opts=OPTS)
444   raise(InvalidOperation, "INTERSECT not supported") unless supports_intersect_except?
445   raise(InvalidOperation, "INTERSECT ALL not supported") if opts[:all] && !supports_intersect_except_all?
446   compound_clone(:intersect, dataset, opts)
447 end
invert() click to toggle source

Inverts the current WHERE and HAVING clauses. If there is neither a WHERE or HAVING clause, adds a WHERE clause that is always false.

DB[:items].where(category: 'software').invert
# SELECT * FROM items WHERE (category != 'software')

DB[:items].where(category: 'software', id: 3).invert
# SELECT * FROM items WHERE ((category != 'software') OR (id != 3))

See documentation for exclude for how inversion is handled in regards to SQL 3-valued boolean logic.

    # File lib/sequel/dataset/query.rb
460 def invert
461   cached_dataset(:_invert_ds) do
462     having, where = @opts.values_at(:having, :where)
463     if having.nil? && where.nil?
464       where(false)
465     else
466       o = {}
467       o[:having] = SQL::BooleanExpression.invert(having) if having
468       o[:where] = SQL::BooleanExpression.invert(where) if where
469       clone(o)
470     end
471   end
472 end
join(*args, &block) click to toggle source

Alias of inner_join

    # File lib/sequel/dataset/query.rb
475 def join(*args, &block)
476   inner_join(*args, &block)
477 end
join_table(type, table, expr=nil, options=OPTS) { |table_name, last_alias, opts || EMPTY_ARRAY| ... } click to toggle source

Returns a joined dataset. Not usually called directly, users should use the appropriate join method (e.g. join, left_join, natural_join, cross_join) which fills in the type argument.

Takes the following arguments:

type

The type of join to do (e.g. :inner)

table

table to join into the current dataset. Generally one of the following types:

String, Symbol

identifier used as table or view name

Dataset

a subselect is performed with an alias of tN for some value of N

SQL::Function

set returning function

SQL::AliasedExpression

already aliased expression. Uses given alias unless overridden by the :table_alias option.

expr

conditions used when joining, depends on type:

Hash, Array of pairs

Assumes key (1st arg) is column of joined table (unless already qualified), and value (2nd arg) is column of the last joined or primary table (or the :implicit_qualifier option). To specify multiple conditions on a single joined table column, you must use an array. Uses a JOIN with an ON clause.

Array

If all members of the array are symbols, considers them as columns and uses a JOIN with a USING clause. Most databases will remove duplicate columns from the result set if this is used.

nil

If a block is not given, doesn't use ON or USING, so the JOIN should be a NATURAL or CROSS join. If a block is given, uses an ON clause based on the block, see below.

otherwise

Treats the argument as a filter expression, so strings are considered literal, symbols specify boolean columns, and Sequel expressions can be used. Uses a JOIN with an ON clause.

options

a hash of options, with the following keys supported:

:table_alias

Override the table alias used when joining. In general you shouldn't use this option, you should provide the appropriate SQL::AliasedExpression as the table argument.

:implicit_qualifier

The name to use for qualifying implicit conditions. By default, the last joined or primary table is used.

:join_using

Force the using of JOIN USING, even if expr is not an array of symbols.

:reset_implicit_qualifier

Can set to false to ignore this join when future joins determine qualifier for implicit conditions.

:qualify

Can be set to false to not do any implicit qualification. Can be set to :deep to use the Qualifier AST Transformer, which will attempt to qualify subexpressions of the expression tree. Can be set to :symbol to only qualify symbols. Defaults to the value of default_join_table_qualification.

block

The block argument should only be given if a JOIN with an ON clause is used, in which case it yields the table alias/name for the table currently being joined, the table alias/name for the last joined (or first table), and an array of previous SQL::JoinClause. Unlike where, this block is not treated as a virtual row block.

Examples:

DB[:a].join_table(:cross, :b)
# SELECT * FROM a CROSS JOIN b

DB[:a].join_table(:inner, DB[:b], c: d)
# SELECT * FROM a INNER JOIN (SELECT * FROM b) AS t1 ON (t1.c = a.d)

DB[:a].join_table(:left, Sequel[:b].as(:c), [:d])
# SELECT * FROM a LEFT JOIN b AS c USING (d)

DB[:a].natural_join(:b).join_table(:inner, :c) do |ta, jta, js|
  (Sequel.qualify(ta, :d) > Sequel.qualify(jta, :e)) & {Sequel.qualify(ta, :f)=>DB.from(js.first.table).select(:g)}
end
# SELECT * FROM a NATURAL JOIN b INNER JOIN c
#   ON ((c.d > b.e) AND (c.f IN (SELECT g FROM b)))
    # File lib/sequel/dataset/query.rb
539 def join_table(type, table, expr=nil, options=OPTS, &block)
540   if hoist_cte?(table)
541     s, ds = hoist_cte(table)
542     return s.join_table(type, ds, expr, options, &block)
543   end
544 
545   using_join = options[:join_using] || (expr.is_a?(Array) && !expr.empty? && expr.all?{|x| x.is_a?(Symbol)})
546   if using_join && !supports_join_using?
547     h = {}
548     expr.each{|e| h[e] = e}
549     return join_table(type, table, h, options)
550   end
551 
552   table_alias = options[:table_alias]
553 
554   if table.is_a?(SQL::AliasedExpression)
555     table_expr = if table_alias
556       SQL::AliasedExpression.new(table.expression, table_alias, table.columns)
557     else
558       table
559     end
560     table = table_expr.expression
561     table_name = table_alias = table_expr.alias
562   elsif table.is_a?(Dataset)
563     if table_alias.nil?
564       table_alias_num = (@opts[:num_dataset_sources] || 0) + 1
565       table_alias = dataset_alias(table_alias_num)
566     end
567     table_name = table_alias
568     table_expr = SQL::AliasedExpression.new(table, table_alias)
569   else
570     table, implicit_table_alias = split_alias(table)
571     table_alias ||= implicit_table_alias
572     table_name = table_alias || table
573     table_expr = table_alias ? SQL::AliasedExpression.new(table, table_alias) : table
574   end
575 
576   join = if expr.nil? and !block
577     SQL::JoinClause.new(type, table_expr)
578   elsif using_join
579     raise(Sequel::Error, "can't use a block if providing an array of symbols as expr") if block
580     SQL::JoinUsingClause.new(expr, type, table_expr)
581   else
582     last_alias = options[:implicit_qualifier] || @opts[:last_joined_table] || first_source_alias
583     qualify_type = options[:qualify]
584     if Sequel.condition_specifier?(expr)
585       expr = expr.map do |k, v|
586         qualify_type = default_join_table_qualification if qualify_type.nil?
587         case qualify_type
588         when false
589           nil # Do no qualification
590         when :deep
591           k = Sequel::Qualifier.new(table_name).transform(k)
592           v = Sequel::Qualifier.new(last_alias).transform(v)
593         else
594           k = qualified_column_name(k, table_name) if k.is_a?(Symbol)
595           v = qualified_column_name(v, last_alias) if v.is_a?(Symbol)
596         end
597         [k,v]
598       end
599       expr = SQL::BooleanExpression.from_value_pairs(expr)
600     end
601     if block
602       expr2 = yield(table_name, last_alias, @opts[:join] || EMPTY_ARRAY)
603       expr = expr ? SQL::BooleanExpression.new(:AND, expr, expr2) : expr2
604     end
605     SQL::JoinOnClause.new(expr, type, table_expr)
606   end
607 
608   opts = {:join => ((@opts[:join] || EMPTY_ARRAY) + [join]).freeze}
609   opts[:last_joined_table] = table_name unless options[:reset_implicit_qualifier] == false
610   opts[:num_dataset_sources] = table_alias_num if table_alias_num
611   clone(opts)
612 end
lateral() click to toggle source

Marks this dataset as a lateral dataset. If used in another dataset's FROM or JOIN clauses, it will surround the subquery with LATERAL to enable it to deal with previous tables in the query:

DB.from(:a, DB[:b].where(Sequel[:a][:c]=>Sequel[:b][:d]).lateral)
# SELECT * FROM a, LATERAL (SELECT * FROM b WHERE (a.c = b.d))
    # File lib/sequel/dataset/query.rb
633 def lateral
634   cached_dataset(:_lateral_ds){clone(:lateral=>true)}
635 end
limit(l, o = (no_offset = true; nil)) click to toggle source

If given an integer, the dataset will contain only the first l results. If given a range, it will contain only those at offsets within that range. If a second argument is given, it is used as an offset. To use an offset without a limit, pass nil as the first argument.

DB[:items].limit(10) # SELECT * FROM items LIMIT 10
DB[:items].limit(10, 20) # SELECT * FROM items LIMIT 10 OFFSET 20
DB[:items].limit(10...20) # SELECT * FROM items LIMIT 10 OFFSET 10
DB[:items].limit(10..20) # SELECT * FROM items LIMIT 11 OFFSET 10
DB[:items].limit(nil, 20) # SELECT * FROM items OFFSET 20
    # File lib/sequel/dataset/query.rb
647 def limit(l, o = (no_offset = true; nil))
648   return from_self.limit(l, o) if @opts[:sql]
649 
650   if l.is_a?(Range)
651     no_offset = false
652     o = l.first
653     l = l.last - l.first + (l.exclude_end? ? 0 : 1)
654   end
655   l = l.to_i if l.is_a?(String) && !l.is_a?(LiteralString)
656   if l.is_a?(Integer)
657     raise(Error, 'Limits must be greater than or equal to 1') unless l >= 1
658   end
659 
660   ds = clone(:limit=>l)
661   ds = ds.offset(o) unless no_offset
662   ds
663 end
lock_style(style) click to toggle source

Returns a cloned dataset with the given lock style. If style is a string, it will be used directly. You should never pass a string to this method that is derived from user input, as that can lead to SQL injection.

A symbol may be used for database independent locking behavior, but all supported symbols have separate methods (e.g. for_update).

DB[:items].lock_style('FOR SHARE NOWAIT')
# SELECT * FROM items FOR SHARE NOWAIT
DB[:items].lock_style('FOR UPDATE OF table1 SKIP LOCKED')
# SELECT * FROM items FOR UPDATE OF table1 SKIP LOCKED
    # File lib/sequel/dataset/query.rb
677 def lock_style(style)
678   clone(:lock => style)
679 end
merge_delete(&block) click to toggle source

Return a dataset with a WHEN MATCHED THEN DELETE clause added to the MERGE statement. If a block is passed, treat it as a virtual row and use it as additional conditions for the match.

merge_delete
# WHEN MATCHED THEN DELETE

merge_delete{a > 30}
# WHEN MATCHED AND (a > 30) THEN DELETE
    # File lib/sequel/dataset/query.rb
690 def merge_delete(&block)
691   _merge_when(:type=>:delete, &block)
692 end
merge_insert(*values, &block) click to toggle source

Return a dataset with a WHEN NOT MATCHED THEN INSERT clause added to the MERGE statement. If a block is passed, treat it as a virtual row and use it as additional conditions for the match.

The arguments provided can be any arguments that would be accepted by insert.

merge_insert(i1: :i2, a: Sequel[:b]+11)
# WHEN NOT MATCHED THEN INSERT (i1, a) VALUES (i2, (b + 11))

merge_insert(:i2, Sequel[:b]+11){a > 30}
# WHEN NOT MATCHED AND (a > 30) THEN INSERT VALUES (i2, (b + 11))
    # File lib/sequel/dataset/query.rb
706 def merge_insert(*values, &block)
707   _merge_when(:type=>:insert, :values=>values, &block)
708 end
merge_update(values, &block) click to toggle source

Return a dataset with a WHEN MATCHED THEN UPDATE clause added to the MERGE statement. If a block is passed, treat it as a virtual row and use it as additional conditions for the match.

merge_update(i1: Sequel[:i1]+:i2+10, a: Sequel[:a]+:b+20)
# WHEN MATCHED THEN UPDATE SET i1 = (i1 + i2 + 10), a = (a + b + 20)

merge_update(i1: :i2){a > 30}
# WHEN MATCHED AND (a > 30) THEN UPDATE SET i1 = i2
    # File lib/sequel/dataset/query.rb
719 def merge_update(values, &block)
720   _merge_when(:type=>:update, :values=>values, &block)
721 end
merge_using(source, join_condition) click to toggle source

Return a dataset with the source and join condition to use for the MERGE statement.

merge_using(:m2, i1: :i2)
# USING m2 ON (i1 = i2)
    # File lib/sequel/dataset/query.rb
727 def merge_using(source, join_condition)
728   clone(:merge_using => [source, join_condition].freeze)
729 end
naked() click to toggle source

Returns a cloned dataset without a row_proc.

ds = DB[:items].with_row_proc(:invert.to_proc)
ds.all # => [{2=>:id}]
ds.naked.all # => [{:id=>2}]
    # File lib/sequel/dataset/query.rb
736 def naked
737   cached_dataset(:_naked_ds){with_row_proc(nil)}
738 end
nowait() click to toggle source

Returns a copy of the dataset that will raise a DatabaseLockTimeout instead of waiting for rows that are locked by another transaction

DB[:items].for_update.nowait
# SELECT * FROM items FOR UPDATE NOWAIT
    # File lib/sequel/dataset/query.rb
745 def nowait
746   cached_dataset(:_nowait_ds) do
747     raise(Error, 'This dataset does not support raises errors instead of waiting for locked rows') unless supports_nowait?
748     clone(:nowait=>true)
749   end
750 end
offset(o) click to toggle source

Returns a copy of the dataset with a specified order. Can be safely combined with limit. If you call limit with an offset, it will override the offset if you've called offset first.

DB[:items].offset(10) # SELECT * FROM items OFFSET 10
    # File lib/sequel/dataset/query.rb
757 def offset(o)
758   o = o.to_i if o.is_a?(String) && !o.is_a?(LiteralString)
759   if o.is_a?(Integer)
760     raise(Error, 'Offsets must be greater than or equal to 0') unless o >= 0
761   end
762   clone(:offset => o)
763 end
or(*cond, &block) click to toggle source

Adds an alternate filter to an existing WHERE clause using OR. If there is no WHERE clause, then the default is WHERE true, and OR would be redundant, so return the dataset in that case.

DB[:items].where(:a).or(:b) # SELECT * FROM items WHERE a OR b
DB[:items].or(:b) # SELECT * FROM items
    # File lib/sequel/dataset/query.rb
771 def or(*cond, &block)
772   if @opts[:where].nil?
773     self
774   else
775     add_filter(:where, cond, false, :OR, &block)
776   end
777 end
order(*columns, &block) click to toggle source

Returns a copy of the dataset with the order changed. If the dataset has an existing order, it is ignored and overwritten with this order. If a nil is given the returned dataset has no order. This can accept multiple arguments of varying kinds, such as SQL functions. If a block is given, it is treated as a virtual row block, similar to where.

DB[:items].order(:name) # SELECT * FROM items ORDER BY name
DB[:items].order(:a, :b) # SELECT * FROM items ORDER BY a, b
DB[:items].order(Sequel.lit('a + b')) # SELECT * FROM items ORDER BY a + b
DB[:items].order(Sequel[:a] + :b) # SELECT * FROM items ORDER BY (a + b)
DB[:items].order(Sequel.desc(:name)) # SELECT * FROM items ORDER BY name DESC
DB[:items].order(Sequel.asc(:name, :nulls=>:last)) # SELECT * FROM items ORDER BY name ASC NULLS LAST
DB[:items].order{sum(name).desc} # SELECT * FROM items ORDER BY sum(name) DESC
DB[:items].order(nil) # SELECT * FROM items
    # File lib/sequel/dataset/query.rb
793 def order(*columns, &block)
794   virtual_row_columns(columns, block)
795   clone(:order => (columns.compact.empty?) ? nil : columns.freeze)
796 end
order_append(*columns, &block) click to toggle source

Returns a copy of the dataset with the order columns added to the end of the existing order.

DB[:items].order(:a).order(:b) # SELECT * FROM items ORDER BY b
DB[:items].order(:a).order_append(:b) # SELECT * FROM items ORDER BY a, b
    # File lib/sequel/dataset/query.rb
803 def order_append(*columns, &block)
804   columns = @opts[:order] + columns if @opts[:order]
805   order(*columns, &block)
806 end
order_by(*columns, &block) click to toggle source

Alias of order

    # File lib/sequel/dataset/query.rb
809 def order_by(*columns, &block)
810   order(*columns, &block)
811 end
order_more(*columns, &block) click to toggle source

Alias of order_append.

    # File lib/sequel/dataset/query.rb
814 def order_more(*columns, &block)
815   order_append(*columns, &block)
816 end
order_prepend(*columns, &block) click to toggle source

Returns a copy of the dataset with the order columns added to the beginning of the existing order.

DB[:items].order(:a).order(:b) # SELECT * FROM items ORDER BY b
DB[:items].order(:a).order_prepend(:b) # SELECT * FROM items ORDER BY b, a
    # File lib/sequel/dataset/query.rb
823 def order_prepend(*columns, &block)
824   ds = order(*columns, &block)
825   @opts[:order] ? ds.order_append(*@opts[:order]) : ds
826 end
qualify(table=(cache=true; first_source)) click to toggle source

Qualify to the given table, or first source if no table is given.

DB[:items].where(id: 1).qualify
# SELECT items.* FROM items WHERE (items.id = 1)

DB[:items].where(id: 1).qualify(:i)
# SELECT i.* FROM items WHERE (i.id = 1)
    # File lib/sequel/dataset/query.rb
835 def qualify(table=(cache=true; first_source))
836   o = @opts
837   return self if o[:sql]
838 
839   pr = proc do
840     h = {}
841     (o.keys & QUALIFY_KEYS).each do |k|
842       h[k] = qualified_expression(o[k], table)
843     end
844     h[:select] = [SQL::ColumnAll.new(table)].freeze if !o[:select] || o[:select].empty?
845     clone(h)
846   end
847 
848   cache ? cached_dataset(:_qualify_ds, &pr) : pr.call
849 end
returning(*values) click to toggle source

Modify the RETURNING clause, only supported on a few databases. If returning is used, instead of insert returning the autogenerated primary key or update/delete returning the number of modified rows, results are returned using fetch_rows.

DB[:items].returning # RETURNING *
DB[:items].returning(nil) # RETURNING NULL
DB[:items].returning(:id, :name) # RETURNING id, name

DB[:items].returning.insert(:a=>1) do |hash|
  # hash for each row inserted, with values for all columns
end
DB[:items].returning.update(:a=>1) do |hash|
  # hash for each row updated, with values for all columns
end
DB[:items].returning.delete(:a=>1) do |hash|
  # hash for each row deleted, with values for all columns
end
    # File lib/sequel/dataset/query.rb
869 def returning(*values)
870   if values.empty?
871     cached_dataset(:_returning_ds) do
872       raise Error, "RETURNING is not supported on #{db.database_type}" unless supports_returning?(:insert)
873       clone(:returning=>EMPTY_ARRAY)
874     end
875   else
876     raise Error, "RETURNING is not supported on #{db.database_type}" unless supports_returning?(:insert)
877     clone(:returning=>values.freeze)
878   end
879 end
reverse(*order, &block) click to toggle source

Returns a copy of the dataset with the order reversed. If no order is given, the existing order is inverted.

DB[:items].reverse(:id) # SELECT * FROM items ORDER BY id DESC
DB[:items].reverse{foo(bar)} # SELECT * FROM items ORDER BY foo(bar) DESC
DB[:items].order(:id).reverse # SELECT * FROM items ORDER BY id DESC
DB[:items].order(:id).reverse(Sequel.desc(:name)) # SELECT * FROM items ORDER BY name ASC
    # File lib/sequel/dataset/query.rb
888 def reverse(*order, &block)
889   if order.empty? && !block
890     cached_dataset(:_reverse_ds){order(*invert_order(@opts[:order]))}
891   else
892     virtual_row_columns(order, block)
893     order(*invert_order(order.empty? ? @opts[:order] : order.freeze))
894   end
895 end
reverse_order(*order, &block) click to toggle source

Alias of reverse

    # File lib/sequel/dataset/query.rb
898 def reverse_order(*order, &block)
899   reverse(*order, &block)
900 end
select(*columns, &block) click to toggle source

Returns a copy of the dataset with the columns selected changed to the given columns. This also takes a virtual row block, similar to where.

DB[:items].select(:a) # SELECT a FROM items
DB[:items].select(:a, :b) # SELECT a, b FROM items
DB[:items].select{[a, sum(b)]} # SELECT a, sum(b) FROM items
    # File lib/sequel/dataset/query.rb
909 def select(*columns, &block)
910   virtual_row_columns(columns, block)
911   clone(:select => columns.freeze)
912 end
select_all(*tables) click to toggle source

Returns a copy of the dataset selecting the wildcard if no arguments are given. If arguments are given, treat them as tables and select all columns (using the wildcard) from each table.

DB[:items].select(:a).select_all # SELECT * FROM items
DB[:items].select_all(:items) # SELECT items.* FROM items
DB[:items].select_all(:items, :foo) # SELECT items.*, foo.* FROM items
    # File lib/sequel/dataset/query.rb
921 def select_all(*tables)
922   if tables.empty?
923     cached_dataset(:_select_all_ds){clone(:select => nil)}
924   else
925     select(*tables.map{|t| i, a = split_alias(t); a || i}.map!{|t| SQL::ColumnAll.new(t)}.freeze)
926   end
927 end
select_append(*columns, &block) click to toggle source

Returns a copy of the dataset with the given columns added to the existing selected columns. If no columns are currently selected, it will select the columns given in addition to *.

DB[:items].select(:a).select(:b) # SELECT b FROM items
DB[:items].select(:a).select_append(:b) # SELECT a, b FROM items
DB[:items].select_append(:b) # SELECT *, b FROM items
    # File lib/sequel/dataset/query.rb
936 def select_append(*columns, &block)
937   cur_sel = @opts[:select]
938   if !cur_sel || cur_sel.empty?
939     unless supports_select_all_and_column?
940       return select_all(*(Array(@opts[:from]) + Array(@opts[:join]))).select_append(*columns, &block)
941     end
942     cur_sel = [WILDCARD]
943   end
944   select(*(cur_sel + columns), &block)
945 end
select_group(*columns, &block) click to toggle source

Set both the select and group clauses with the given columns. Column aliases may be supplied, and will be included in the select clause. This also takes a virtual row block similar to where.

DB[:items].select_group(:a, :b)
# SELECT a, b FROM items GROUP BY a, b

DB[:items].select_group(Sequel[:c].as(:a)){f(c2)}
# SELECT c AS a, f(c2) FROM items GROUP BY c, f(c2)
    # File lib/sequel/dataset/query.rb
956 def select_group(*columns, &block)
957   virtual_row_columns(columns, block)
958   select(*columns).group(*columns.map{|c| unaliased_identifier(c)})
959 end
select_more(*columns, &block) click to toggle source

Alias for select_append.

    # File lib/sequel/dataset/query.rb
962 def select_more(*columns, &block)
963   select_append(*columns, &block)
964 end
server(servr) click to toggle source

Set the server for this dataset to use. Used to pick a specific database shard to run a query against, or to override the default (where SELECT uses :read_only database and all other queries use the :default database). This method is always available but is only useful when database sharding is being used.

DB[:items].all # Uses the :read_only or :default server
DB[:items].delete # Uses the :default server
DB[:items].server(:blah).delete # Uses the :blah server
    # File lib/sequel/dataset/query.rb
975 def server(servr)
976   clone(:server=>servr)
977 end
server?(server) click to toggle source

If the database uses sharding and the current dataset has not had a server set, return a cloned dataset that uses the given server. Otherwise, return the receiver directly instead of returning a clone.

    # File lib/sequel/dataset/query.rb
982 def server?(server)
983   if db.sharded? && !opts[:server]
984     server(server)
985   else
986     self
987   end
988 end
skip_limit_check() click to toggle source

Specify that the check for limits/offsets when updating/deleting be skipped for the dataset.

    # File lib/sequel/dataset/query.rb
991 def skip_limit_check
992   cached_dataset(:_skip_limit_check_ds) do
993     clone(:skip_limit_check=>true)
994   end
995 end
skip_locked() click to toggle source

Skip locked rows when returning results from this dataset.

     # File lib/sequel/dataset/query.rb
 998 def skip_locked
 999   cached_dataset(:_skip_locked_ds) do
1000     raise(Error, 'This dataset does not support skipping locked rows') unless supports_skip_locked?
1001     clone(:skip_locked=>true)
1002   end
1003 end
unfiltered() click to toggle source

Returns a copy of the dataset with no filters (HAVING or WHERE clause) applied.

DB[:items].group(:a).having(a: 1).where(:b).unfiltered
# SELECT * FROM items GROUP BY a
     # File lib/sequel/dataset/query.rb
1009 def unfiltered
1010   cached_dataset(:_unfiltered_ds){clone(:where => nil, :having => nil)}
1011 end
ungrouped() click to toggle source

Returns a copy of the dataset with no grouping (GROUP or HAVING clause) applied.

DB[:items].group(:a).having(a: 1).where(:b).ungrouped
# SELECT * FROM items WHERE b
     # File lib/sequel/dataset/query.rb
1017 def ungrouped
1018   cached_dataset(:_ungrouped_ds){clone(:group => nil, :having => nil)}
1019 end
union(dataset, opts=OPTS) click to toggle source

Adds a UNION clause using a second dataset object. A UNION compound dataset returns all rows in either the current dataset or the given dataset. Options:

:alias

Use the given value as the from_self alias

:all

Set to true to use UNION ALL instead of UNION, so duplicate rows can occur

:from_self

Set to false to not wrap the returned dataset in a from_self, use with care.

DB[:items].union(DB[:other_items])
# SELECT * FROM (SELECT * FROM items UNION SELECT * FROM other_items) AS t1

DB[:items].union(DB[:other_items], all: true, from_self: false)
# SELECT * FROM items UNION ALL SELECT * FROM other_items

DB[:items].union(DB[:other_items], alias: :i)
# SELECT * FROM (SELECT * FROM items UNION SELECT * FROM other_items) AS i
     # File lib/sequel/dataset/query.rb
1037 def union(dataset, opts=OPTS)
1038   compound_clone(:union, dataset, opts)
1039 end
unlimited() click to toggle source

Returns a copy of the dataset with no limit or offset.

DB[:items].limit(10, 20).unlimited # SELECT * FROM items
     # File lib/sequel/dataset/query.rb
1044 def unlimited
1045   cached_dataset(:_unlimited_ds){clone(:limit=>nil, :offset=>nil)}
1046 end
unordered() click to toggle source

Returns a copy of the dataset with no order.

DB[:items].order(:a).unordered # SELECT * FROM items
     # File lib/sequel/dataset/query.rb
1051 def unordered
1052   cached_dataset(:_unordered_ds){clone(:order=>nil)}
1053 end
where(*cond, &block) click to toggle source

Returns a copy of the dataset with the given WHERE conditions imposed upon it.

Accepts the following argument types:

Hash, Array of pairs

list of equality/inclusion expressions

Symbol

taken as a boolean column argument (e.g. WHERE active)

Sequel::SQL::BooleanExpression, Sequel::LiteralString

an existing condition expression, probably created using the Sequel expression filter DSL.

where also accepts a block, which should return one of the above argument types, and is treated the same way. This block yields a virtual row object, which is easy to use to create identifiers and functions. For more details on the virtual row support, see the “Virtual Rows” guide

If both a block and regular argument are provided, they get ANDed together.

Examples:

DB[:items].where(id: 3)
# SELECT * FROM items WHERE (id = 3)

DB[:items].where(Sequel.lit('price < ?', 100))
# SELECT * FROM items WHERE price < 100

DB[:items].where([[:id, [1,2,3]], [:id, 0..10]])
# SELECT * FROM items WHERE ((id IN (1, 2, 3)) AND ((id >= 0) AND (id <= 10)))

DB[:items].where(Sequel.lit('price < 100'))
# SELECT * FROM items WHERE price < 100

DB[:items].where(:active)
# SELECT * FROM items WHERE :active

DB[:items].where{price < 100}
# SELECT * FROM items WHERE (price < 100)

Multiple where calls can be chained for scoping:

software = dataset.where(category: 'software').where{price < 100}
# SELECT * FROM items WHERE ((category = 'software') AND (price < 100))

See the “Dataset Filtering” guide for more examples and details.

     # File lib/sequel/dataset/query.rb
1097 def where(*cond, &block)
1098   add_filter(:where, cond, &block)
1099 end
window(name, opts) click to toggle source

Return a clone of the dataset with an addition named window that can be referenced in window functions. See Sequel::SQL::Window for a list of options that can be passed in. Example:

DB[:items].window(:w, :partition=>:c1, :order=>:c2)
# SELECT * FROM items WINDOW w AS (PARTITION BY c1 ORDER BY c2)
     # File lib/sequel/dataset/query.rb
1107 def window(name, opts)
1108   clone(:window=>((@opts[:window]||EMPTY_ARRAY) + [[name, SQL::Window.new(opts)].freeze]).freeze)
1109 end
with(name, dataset, opts=OPTS) click to toggle source

Add a common table expression (CTE) with the given name and a dataset that defines the CTE. A common table expression acts as an inline view for the query.

Options:

:args

Specify the arguments/columns for the CTE, should be an array of symbols.

:recursive

Specify that this is a recursive CTE

:materialized

Set to false to force inlining of the CTE, or true to force not inlining the CTE (PostgreSQL 12+/SQLite 3.35+).

DB[:items].with(:items, DB[:syx].where(Sequel[:name].like('A%')))
# WITH items AS (SELECT * FROM syx WHERE (name LIKE 'A%' ESCAPE '\')) SELECT * FROM items
     # File lib/sequel/dataset/query.rb
1122 def with(name, dataset, opts=OPTS)
1123   raise(Error, 'This dataset does not support common table expressions') unless supports_cte?
1124   if hoist_cte?(dataset)
1125     s, ds = hoist_cte(dataset)
1126     s.with(name, ds, opts)
1127   else
1128     clone(:with=>((@opts[:with]||EMPTY_ARRAY) + [Hash[opts].merge!(:name=>name, :dataset=>dataset)]).freeze)
1129   end
1130 end
with_extend(*mods, &block) click to toggle source

Return a clone of the dataset extended with the given modules. Note that like Object#extend, when multiple modules are provided as arguments the cloned dataset is extended with the modules in reverse order. If a block is provided, a DatasetModule is created using the block and the clone is extended with that module after any modules given as arguments.

     # File lib/sequel/dataset/query.rb
1207 def with_extend(*mods, &block)
1208   c = _clone(:freeze=>false)
1209   c.extend(*mods) unless mods.empty?
1210   c.extend(DatasetModule.new(&block)) if block
1211   c.freeze
1212 end
with_recursive(name, nonrecursive, recursive, opts=OPTS) click to toggle source

Add a recursive common table expression (CTE) with the given name, a dataset that defines the nonrecursive part of the CTE, and a dataset that defines the recursive part of the CTE.

Options:

:args

Specify the arguments/columns for the CTE, should be an array of symbols.

:union_all

Set to false to use UNION instead of UNION ALL combining the nonrecursive and recursive parts.

PostgreSQL 14+ Options:

:cycle

Stop recursive searching when a cycle is detected. Includes two columns in the result of the CTE, a cycle column indicating whether a cycle was detected for the current row, and a path column for the path traversed to get to the current row. If given, must be a hash with the following keys:

:columns

(required) The column or array of columns to use to detect a cycle. If the value of these columns match columns already traversed, then a cycle is detected, and recursive searching will not traverse beyond the cycle (the CTE will include the row where the cycle was detected).

:cycle_column

The name of the cycle column in the output, defaults to :is_cycle.

:cycle_value

The value of the cycle column in the output if the current row was detected as a cycle, defaults to true.

:noncycle_value

The value of the cycle column in the output if the current row was not detected as a cycle, defaults to false. Only respected if :cycle_value is given.

:path_column

The name of the path column in the output, defaults to :path.

:search

Include an order column in the result of the CTE that allows for breadth or depth first searching. If given, must be a hash with the following keys:

:by

(required) The column or array of columns to search by.

:order_column

The name of the order column in the output, defaults to :ordercol.

:type

Set to :breadth to use breadth-first searching (depth-first searching is the default).

DB[:t].with_recursive(:t,
  DB[:i1].select(:id, :parent_id).where(parent_id: nil),
  DB[:i1].join(:t, id: :parent_id).select(Sequel[:i1][:id], Sequel[:i1][:parent_id]),
  :args=>[:id, :parent_id])

# WITH RECURSIVE t(id, parent_id) AS (
#   SELECT id, parent_id FROM i1 WHERE (parent_id IS NULL)
#   UNION ALL
#   SELECT i1.id, i1.parent_id FROM i1 INNER JOIN t ON (t.id = i1.parent_id)
# ) SELECT * FROM t

DB[:t].with_recursive(:t,
  DB[:i1].where(parent_id: nil),
  DB[:i1].join(:t, id: :parent_id).select_all(:i1),
  search: {by: :id, type: :breadth},
  cycle: {columns: :id, cycle_value: 1, noncycle_value: 2})

# WITH RECURSIVE t AS (
#     SELECT * FROM i1 WHERE (parent_id IS NULL)
#     UNION ALL
#     (SELECT i1.* FROM i1 INNER JOIN t ON (t.id = i1.parent_id))
#   )
#   SEARCH BREADTH FIRST BY id SET ordercol
#   CYCLE id SET is_cycle TO 1 DEFAULT 2 USING path
# SELECT * FROM t
     # File lib/sequel/dataset/query.rb
1188 def with_recursive(name, nonrecursive, recursive, opts=OPTS)
1189   raise(Error, 'This dataset does not support common table expressions') unless supports_cte?
1190   if hoist_cte?(nonrecursive)
1191     s, ds = hoist_cte(nonrecursive)
1192     s.with_recursive(name, ds, recursive, opts)
1193   elsif hoist_cte?(recursive)
1194     s, ds = hoist_cte(recursive)
1195     s.with_recursive(name, nonrecursive, ds, opts)
1196   else
1197     clone(:with=>((@opts[:with]||EMPTY_ARRAY) + [Hash[opts].merge!(:recursive=>true, :name=>name, :dataset=>nonrecursive.union(recursive, {:all=>opts[:union_all] != false, :from_self=>false}))]).freeze)
1198   end
1199 end
with_row_proc(callable) click to toggle source

Returns a cloned dataset with the given row_proc.

ds = DB[:items]
ds.all # => [{:id=>2}]
ds.with_row_proc(:invert.to_proc).all # => [{2=>:id}]
     # File lib/sequel/dataset/query.rb
1229 def with_row_proc(callable)
1230   clone(:row_proc=>callable)
1231 end
with_sql(sql, *args) click to toggle source

Returns a copy of the dataset with the static SQL used. This is useful if you want to keep the same row_proc/graph, but change the SQL used to custom SQL.

DB[:items].with_sql('SELECT * FROM foo') # SELECT * FROM foo

You can use placeholders in your SQL and provide arguments for those placeholders:

DB[:items].with_sql('SELECT ? FROM foo', 1) # SELECT 1 FROM foo

You can also provide a method name and arguments to call to get the SQL:

DB[:items].with_sql(:insert_sql, :b=>1) # INSERT INTO items (b) VALUES (1)

Note that datasets that specify custom SQL using this method will generally ignore future dataset methods that modify the SQL used, as specifying custom SQL overrides Sequel's SQL generator. You should probably limit yourself to the following dataset methods when using this method, or use the implicit_subquery extension:

  • each

  • all

  • single_record (if only one record could be returned)

  • single_value (if only one record could be returned, and a single column is selected)

  • map

  • as_hash

  • to_hash

  • to_hash_groups

  • delete (if a DELETE statement)

  • update (if an UPDATE statement, with no arguments)

  • insert (if an INSERT statement, with no arguments)

  • truncate (if a TRUNCATE statement, with no arguments)

     # File lib/sequel/dataset/query.rb
1263 def with_sql(sql, *args)
1264   if sql.is_a?(Symbol)
1265     sql = public_send(sql, *args)
1266   else
1267     sql = SQL::PlaceholderLiteralString.new(sql, args) unless args.empty?
1268   end
1269   clone(:sql=>sql)
1270 end

Protected Instance Methods

compound_clone(type, dataset, opts) click to toggle source

Add the dataset to the list of compounds

     # File lib/sequel/dataset/query.rb
1275 def compound_clone(type, dataset, opts)
1276   if dataset.is_a?(Dataset) && dataset.opts[:with] && !supports_cte_in_compounds?
1277     s, ds = hoist_cte(dataset)
1278     return s.compound_clone(type, ds, opts)
1279   end
1280   ds = compound_from_self.clone(:compounds=>(Array(@opts[:compounds]).map(&:dup) + [[type, dataset.compound_from_self, opts[:all]].freeze]).freeze)
1281   opts[:from_self] == false ? ds : ds.from_self(opts)
1282 end
options_overlap(opts) click to toggle source

Return true if the dataset has a non-nil value for any key in opts.

     # File lib/sequel/dataset/query.rb
1285 def options_overlap(opts)
1286   !(@opts.map{|k,v| k unless v.nil?}.compact & opts).empty?
1287 end
simple_select_all?() click to toggle source

Whether this dataset is a simple select from an underlying table, such as:

SELECT * FROM table
SELECT table.* FROM table
     # File lib/sequel/dataset/query.rb
1296 def simple_select_all?
1297   return false unless (f = @opts[:from]) && f.length == 1
1298   o = @opts.reject{|k,v| v.nil? || non_sql_option?(k)}
1299   from = f.first
1300   from = from.expression if from.is_a?(SQL::AliasedExpression)
1301 
1302   if SIMPLE_SELECT_ALL_ALLOWED_FROM.any?{|x| from.is_a?(x)}
1303     case o.length
1304     when 1
1305       true
1306     when 2
1307       (s = o[:select]) && s.length == 1 && s.first.is_a?(SQL::ColumnAll)
1308     else
1309       false
1310     end
1311   else
1312     false
1313   end
1314 end

Private Instance Methods

_extension!(exts) click to toggle source

Load the extensions into the receiver, without checking if the receiver is frozen.

     # File lib/sequel/dataset/query.rb
1319 def _extension!(exts)
1320   Sequel.extension(*exts)
1321   exts.each do |ext|
1322     if pr = Sequel.synchronize{EXTENSIONS[ext]}
1323       pr.call(self)
1324     else
1325       raise(Error, "Extension #{ext} does not have specific support handling individual datasets (try: Sequel.extension #{ext.inspect})")
1326     end
1327   end
1328   self
1329 end
_invert_filter(cond, invert) click to toggle source

If invert is true, invert the condition.

     # File lib/sequel/dataset/query.rb
1332 def _invert_filter(cond, invert)
1333   if invert
1334     SQL::BooleanExpression.invert(cond)
1335   else
1336     cond
1337   end
1338 end
_merge_when(hash, &block) click to toggle source

Append to the current MERGE WHEN clauses. Mutates the hash to add the conditions, if a virtual row block is passed.

     # File lib/sequel/dataset/query.rb
1342 def _merge_when(hash, &block)
1343   hash[:conditions] = Sequel.virtual_row(&block) if block
1344 
1345   if merge_when = @opts[:merge_when]
1346     clone(:merge_when => (merge_when.dup << hash.freeze).freeze)
1347   else
1348     clone(:merge_when => [hash.freeze].freeze)
1349   end
1350 end
add_filter(clause, cond, invert=false, combine=:AND, &block) click to toggle source

Add the given filter condition. Arguments:

clause

Symbol or which SQL clause to effect, should be :where or :having

cond

The filter condition to add

invert

Whether the condition should be inverted (true or false)

combine

How to combine the condition with an existing condition, should be :AND or :OR

     # File lib/sequel/dataset/query.rb
1357 def add_filter(clause, cond, invert=false, combine=:AND, &block)
1358   if cond == EMPTY_ARRAY && !block
1359     raise Error, "must provide an argument to a filtering method if not passing a block"
1360   end
1361   
1362   cond = cond.first if cond.size == 1
1363 
1364   empty = cond == OPTS || cond == EMPTY_ARRAY
1365 
1366   if empty && !block
1367     self 
1368   else
1369     if cond == nil
1370       cond = Sequel::NULL
1371     end
1372     if empty && block
1373       cond = nil
1374     end
1375 
1376     cond = _invert_filter(filter_expr(cond, &block), invert)
1377     cond = SQL::BooleanExpression.new(combine, @opts[clause], cond) if @opts[clause]
1378 
1379     if cond.nil?
1380       cond = Sequel::NULL
1381     end
1382 
1383     clone(clause => cond)
1384   end
1385 end
default_join_table_qualification() click to toggle source

The default :qualify option to use for join tables if one is not specified.

     # File lib/sequel/dataset/query.rb
1388 def default_join_table_qualification
1389   :symbol
1390 end
default_server() click to toggle source

Return self if the dataset already has a server, or a cloned dataset with the default server otherwise.

     # File lib/sequel/dataset/query.rb
1463 def default_server
1464   server?(:default)
1465 end
filter_expr(expr = nil, &block) click to toggle source

SQL expression object based on the expr type. See where.

     # File lib/sequel/dataset/query.rb
1393 def filter_expr(expr = nil, &block)
1394   expr = nil if expr == EMPTY_ARRAY
1395 
1396   if block
1397     cond = filter_expr(Sequel.virtual_row(&block))
1398     cond = SQL::BooleanExpression.new(:AND, filter_expr(expr), cond) if expr
1399     return cond
1400   end
1401 
1402   case expr
1403   when Hash
1404     SQL::BooleanExpression.from_value_pairs(expr)
1405   when Array
1406     if Sequel.condition_specifier?(expr)
1407       SQL::BooleanExpression.from_value_pairs(expr)
1408     else
1409       raise Error, "Invalid filter expression: #{expr.inspect}"
1410     end
1411   when LiteralString
1412     LiteralString.new("(#{expr})")
1413   when Numeric, SQL::NumericExpression, SQL::StringExpression, Proc, String
1414     raise Error, "Invalid filter expression: #{expr.inspect}"
1415   when TrueClass, FalseClass
1416     if supports_where_true?
1417       SQL::BooleanExpression.new(:NOOP, expr)
1418     elsif expr
1419       SQL::Constants::SQLTRUE
1420     else
1421       SQL::Constants::SQLFALSE
1422     end
1423   when PlaceholderLiteralizer::Argument
1424     expr.transform{|v| filter_expr(v)}
1425   when SQL::PlaceholderLiteralString
1426     expr.with_parens
1427   else
1428     expr
1429   end
1430 end
hoist_cte(ds) click to toggle source

Return two datasets, the first a clone of the receiver with the WITH clause from the given dataset added to it, and the second a clone of the given dataset with the WITH clause removed.

     # File lib/sequel/dataset/query.rb
1435 def hoist_cte(ds)
1436   [clone(:with => ((opts[:with] || EMPTY_ARRAY) + ds.opts[:with]).freeze), ds.clone(:with => nil)]
1437 end
hoist_cte?(ds) click to toggle source

Whether CTEs need to be hoisted from the given ds into the current ds.

     # File lib/sequel/dataset/query.rb
1440 def hoist_cte?(ds)
1441   ds.is_a?(Dataset) && ds.opts[:with] && !supports_cte_in_subqueries?
1442 end
invert_order(order) click to toggle source

Inverts the given order by breaking it into a list of column references and inverting them.

DB[:items].invert_order([Sequel.desc(:id)]]) #=> [Sequel.asc(:id)]
DB[:items].invert_order([:category, Sequel.desc(:price)]) #=> [Sequel.desc(:category), Sequel.asc(:price)]
     # File lib/sequel/dataset/query.rb
1449 def invert_order(order)
1450   return unless order
1451   order.map do |f|
1452     case f
1453     when SQL::OrderedExpression
1454       f.invert
1455     else
1456       SQL::OrderedExpression.new(f)
1457     end
1458   end
1459 end
non_sql_option?(key) click to toggle source

Whether the given option key does not affect the generated SQL.

     # File lib/sequel/dataset/query.rb
1468 def non_sql_option?(key)
1469   NON_SQL_OPTIONS.include?(key)
1470 end
virtual_row_columns(columns, block) click to toggle source

Treat the block as a virtual_row block if not nil and add the resulting columns to the columns array (modifies columns).

     # File lib/sequel/dataset/query.rb
1474 def virtual_row_columns(columns, block)
1475   if block
1476     v = Sequel.virtual_row(&block)
1477     if v.is_a?(Array)
1478       columns.concat(v)
1479     else
1480       columns << v
1481     end
1482   end
1483 end

2 - Methods that execute code on the database

↑ top

Constants

ACTION_METHODS

Action methods defined by Sequel that execute code on the database.

COLUMNS_CLONE_OPTIONS

The clone options to use when retrieving columns for a dataset.

COUNT_SELECT
EMPTY_SELECT

Public Instance Methods

<<(arg) click to toggle source

Inserts the given argument into the database. Returns self so it can be used safely when chaining:

DB[:items] << {id: 0, name: 'Zero'} << DB[:old_items].select(:id, name)
   # File lib/sequel/dataset/actions.rb
28 def <<(arg)
29   insert(arg)
30   self
31 end
[](*conditions) click to toggle source

Returns the first record matching the conditions. Examples:

DB[:table][id: 1] # SELECT * FROM table WHERE (id = 1) LIMIT 1
# => {:id=>1}
   # File lib/sequel/dataset/actions.rb
37 def [](*conditions)
38   raise(Error, 'You cannot call Dataset#[] with an integer or with no arguments') if (conditions.length == 1 and conditions.first.is_a?(Integer)) or conditions.length == 0
39   first(*conditions)
40 end
all(&block) click to toggle source

Returns an array with all records in the dataset. If a block is given, the array is iterated over after all items have been loaded.

DB[:table].all # SELECT * FROM table
# => [{:id=>1, ...}, {:id=>2, ...}, ...]

# Iterate over all rows in the table
DB[:table].all{|row| p row}
   # File lib/sequel/dataset/actions.rb
50 def all(&block)
51   _all(block){|a| each{|r| a << r}}
52 end
as_hash(key_column, value_column = nil, opts = OPTS) click to toggle source

Returns a hash with one column used as key and another used as value. If rows have duplicate values for the key column, the latter row(s) will overwrite the value of the previous row(s). If the value_column is not given or nil, uses the entire hash as the value.

DB[:table].as_hash(:id, :name) # SELECT * FROM table
# {1=>'Jim', 2=>'Bob', ...}

DB[:table].as_hash(:id) # SELECT * FROM table
# {1=>{:id=>1, :name=>'Jim'}, 2=>{:id=>2, :name=>'Bob'}, ...}

You can also provide an array of column names for either the key_column, the value column, or both:

DB[:table].as_hash([:id, :foo], [:name, :bar]) # SELECT * FROM table
# {[1, 3]=>['Jim', 'bo'], [2, 4]=>['Bob', 'be'], ...}

DB[:table].as_hash([:id, :name]) # SELECT * FROM table
# {[1, 'Jim']=>{:id=>1, :name=>'Jim'}, [2, 'Bob']=>{:id=>2, :name=>'Bob'}, ...}

Options:

:all

Use all instead of each to retrieve the objects

:hash

The object into which the values will be placed. If this is not given, an empty hash is used. This can be used to use a hash with a default value or default proc.

    # File lib/sequel/dataset/actions.rb
823 def as_hash(key_column, value_column = nil, opts = OPTS)
824   h = opts[:hash] || {}
825   meth = opts[:all] ? :all : :each
826   if value_column
827     return naked.as_hash(key_column, value_column, opts) if row_proc
828     if value_column.is_a?(Array)
829       if key_column.is_a?(Array)
830         public_send(meth){|r| h[r.values_at(*key_column)] = r.values_at(*value_column)}
831       else
832         public_send(meth){|r| h[r[key_column]] = r.values_at(*value_column)}
833       end
834     else
835       if key_column.is_a?(Array)
836         public_send(meth){|r| h[r.values_at(*key_column)] = r[value_column]}
837       else
838         public_send(meth){|r| h[r[key_column]] = r[value_column]}
839       end
840     end
841   elsif key_column.is_a?(Array)
842     public_send(meth){|r| h[key_column.map{|k| r[k]}] = r}
843   else
844     public_send(meth){|r| h[r[key_column]] = r}
845   end
846   h
847 end
avg(arg=(no_arg = true), &block) click to toggle source

Returns the average value for the given column/expression. Uses a virtual row block if no argument is given.

DB[:table].avg(:number) # SELECT avg(number) FROM table LIMIT 1
# => 3
DB[:table].avg{function(column)} # SELECT avg(function(column)) FROM table LIMIT 1
# => 1
   # File lib/sequel/dataset/actions.rb
61 def avg(arg=(no_arg = true), &block)
62   arg = Sequel.virtual_row(&block) if no_arg
63   _aggregate(:avg, arg)
64 end
columns() click to toggle source

Returns the columns in the result set in order as an array of symbols. If the columns are currently cached, returns the cached value. Otherwise, a SELECT query is performed to retrieve a single row in order to get the columns.

If you are looking for all columns for a single table and maybe some information about each column (e.g. database type), see Database#schema.

DB[:table].columns
# => [:id, :name]
   # File lib/sequel/dataset/actions.rb
75 def columns
76   _columns || columns!
77 end
columns!() click to toggle source

Ignore any cached column information and perform a query to retrieve a row in order to get the columns.

DB[:table].columns!
# => [:id, :name]
   # File lib/sequel/dataset/actions.rb
84 def columns!
85   ds = clone(COLUMNS_CLONE_OPTIONS)
86   ds.each{break}
87 
88   if cols = ds.cache[:_columns]
89     self.columns = cols
90   else
91     []
92   end
93 end
count(arg=(no_arg=true), &block) click to toggle source

Returns the number of records in the dataset. If an argument is provided, it is used as the argument to count. If a block is provided, it is treated as a virtual row, and the result is used as the argument to count.

DB[:table].count # SELECT count(*) AS count FROM table LIMIT 1
# => 3
DB[:table].count(:column) # SELECT count(column) AS count FROM table LIMIT 1
# => 2
DB[:table].count{foo(column)} # SELECT count(foo(column)) AS count FROM table LIMIT 1
# => 1
    # File lib/sequel/dataset/actions.rb
108 def count(arg=(no_arg=true), &block)
109   if no_arg && !block
110     cached_dataset(:_count_ds) do
111       aggregate_dataset.select(COUNT_SELECT).single_value_ds
112     end.single_value!.to_i
113   else
114     if block
115       if no_arg
116         arg = Sequel.virtual_row(&block)
117       else
118         raise Error, 'cannot provide both argument and block to Dataset#count'
119       end
120     end
121 
122     _aggregate(:count, arg)
123   end
124 end
delete(&block) click to toggle source

Deletes the records in the dataset, returning the number of records deleted.

DB[:table].delete # DELETE * FROM table
# => 3
    # File lib/sequel/dataset/actions.rb
130 def delete(&block)
131   sql = delete_sql
132   if uses_returning?(:delete)
133     returning_fetch_rows(sql, &block)
134   else
135     execute_dui(sql)
136   end
137 end
each() { |call| ... } click to toggle source

Iterates over the records in the dataset as they are yielded from the database adapter, and returns self.

DB[:table].each{|row| p row} # SELECT * FROM table

Note that this method is not safe to use on many adapters if you are running additional queries inside the provided block. If you are running queries inside the block, you should use all instead of each for the outer queries, or use a separate thread or shard inside each.

    # File lib/sequel/dataset/actions.rb
148 def each
149   if rp = row_proc
150     fetch_rows(select_sql){|r| yield rp.call(r)}
151   else
152     fetch_rows(select_sql){|r| yield r}
153   end
154   self
155 end
empty?() click to toggle source

Returns true if no records exist in the dataset, false otherwise

DB[:table].empty? # SELECT 1 AS one FROM table LIMIT 1
# => false
    # File lib/sequel/dataset/actions.rb
163 def empty?
164   cached_dataset(:_empty_ds) do
165     single_value_ds.unordered.select(EMPTY_SELECT)
166   end.single_value!.nil?
167 end
first(*args, &block) click to toggle source

Returns the first matching record if no arguments are given. If a integer argument is given, it is interpreted as a limit, and then returns all matching records up to that limit. If any other type of argument(s) is passed, it is treated as a filter and the first matching record is returned. If a block is given, it is used to filter the dataset before returning anything.

If there are no records in the dataset, returns nil (or an empty array if an integer argument is given).

Examples:

DB[:table].first # SELECT * FROM table LIMIT 1
# => {:id=>7}

DB[:table].first(2) # SELECT * FROM table LIMIT 2
# => [{:id=>6}, {:id=>4}]

DB[:table].first(id: 2) # SELECT * FROM table WHERE (id = 2) LIMIT 1
# => {:id=>2}

DB[:table].first(Sequel.lit("id = 3")) # SELECT * FROM table WHERE (id = 3) LIMIT 1
# => {:id=>3}

DB[:table].first(Sequel.lit("id = ?", 4)) # SELECT * FROM table WHERE (id = 4) LIMIT 1
# => {:id=>4}

DB[:table].first{id > 2} # SELECT * FROM table WHERE (id > 2) LIMIT 1
# => {:id=>5}

DB[:table].first(Sequel.lit("id > ?", 4)){id < 6} # SELECT * FROM table WHERE ((id > 4) AND (id < 6)) LIMIT 1
# => {:id=>5}

DB[:table].first(2){id < 2} # SELECT * FROM table WHERE (id < 2) LIMIT 2
# => [{:id=>1}]
    # File lib/sequel/dataset/actions.rb
204 def first(*args, &block)
205   case args.length
206   when 0
207     unless block
208       return single_record
209     end
210   when 1
211     arg = args[0]
212     if arg.is_a?(Integer)
213       res = if block
214         if loader = cached_placeholder_literalizer(:_first_integer_cond_loader) do |pl|
215             where(pl.arg).limit(pl.arg)
216           end
217 
218           loader.all(filter_expr(&block), arg)
219         else
220           where(&block).limit(arg).all
221         end
222       else
223         if loader = cached_placeholder_literalizer(:_first_integer_loader) do |pl|
224            limit(pl.arg)
225           end
226 
227           loader.all(arg)
228         else
229           limit(arg).all
230         end
231       end
232 
233       return res
234     end
235     where_args = args
236     args = arg
237   end
238 
239   if loader = cached_where_placeholder_literalizer(where_args||args, block, :_first_cond_loader) do |pl|
240       _single_record_ds.where(pl.arg)
241     end
242 
243     loader.first(filter_expr(args, &block))
244   else
245     _single_record_ds.where(args, &block).single_record!
246   end
247 end
first!(*args, &block) click to toggle source

Calls first. If first returns nil (signaling that no row matches), raise a Sequel::NoMatchingRow exception.

    # File lib/sequel/dataset/actions.rb
251 def first!(*args, &block)
252   first(*args, &block) || raise(Sequel::NoMatchingRow.new(self))
253 end
get(column=(no_arg=true; nil), &block) click to toggle source

Return the column value for the first matching record in the dataset. Raises an error if both an argument and block is given.

DB[:table].get(:id) # SELECT id FROM table LIMIT 1
# => 3

ds.get{sum(id)} # SELECT sum(id) AS v FROM table LIMIT 1
# => 6

You can pass an array of arguments to return multiple arguments, but you must make sure each element in the array has an alias that Sequel can determine:

DB[:table].get([:id, :name]) # SELECT id, name FROM table LIMIT 1
# => [3, 'foo']

DB[:table].get{[sum(id).as(sum), name]} # SELECT sum(id) AS sum, name FROM table LIMIT 1
# => [6, 'foo']
    # File lib/sequel/dataset/actions.rb
273 def get(column=(no_arg=true; nil), &block)
274   ds = naked
275   if block
276     raise(Error, 'Must call Dataset#get with an argument or a block, not both') unless no_arg
277     ds = ds.select(&block)
278     column = ds.opts[:select]
279     column = nil if column.is_a?(Array) && column.length < 2
280   else
281     case column
282     when Array
283       ds = ds.select(*column)
284     when LiteralString, Symbol, SQL::Identifier, SQL::QualifiedIdentifier, SQL::AliasedExpression
285       if loader = cached_placeholder_literalizer(:_get_loader) do |pl|
286           ds.single_value_ds.select(pl.arg)
287         end
288 
289         return loader.get(column)
290       end
291 
292       ds = ds.select(column)
293     else
294       if loader = cached_placeholder_literalizer(:_get_alias_loader) do |pl|
295           ds.single_value_ds.select(Sequel.as(pl.arg, :v))
296         end
297 
298         return loader.get(column)
299       end
300 
301       ds = ds.select(Sequel.as(column, :v))
302     end
303   end
304 
305   if column.is_a?(Array)
306    if r = ds.single_record
307      r.values_at(*hash_key_symbols(column))
308    end
309   else
310     ds.single_value
311   end
312 end
import(columns, values, opts=OPTS) click to toggle source

Inserts multiple records into the associated table. This method can be used to efficiently insert a large number of records into a table in a single query if the database supports it. Inserts are automatically wrapped in a transaction.

This method is called with a columns array and an array of value arrays:

DB[:table].import([:x, :y], [[1, 2], [3, 4]])
# INSERT INTO table (x, y) VALUES (1, 2)
# INSERT INTO table (x, y) VALUES (3, 4)

This method also accepts a dataset instead of an array of value arrays:

DB[:table].import([:x, :y], DB[:table2].select(:a, :b))
# INSERT INTO table (x, y) SELECT a, b FROM table2

Options:

:commit_every

Open a new transaction for every given number of records. For example, if you provide a value of 50, will commit after every 50 records.

:return

When this is set to :primary_key, returns an array of autoincremented primary key values for the rows inserted. This does not have an effect if values is a Dataset.

:server

Set the server/shard to use for the transaction and insert queries.

:slice

Same as :commit_every, :commit_every takes precedence.

    # File lib/sequel/dataset/actions.rb
340 def import(columns, values, opts=OPTS)
341   return @db.transaction{insert(columns, values)} if values.is_a?(Dataset)
342 
343   return if values.empty?
344   raise(Error, 'Using Sequel::Dataset#import with an empty column array is not allowed') if columns.empty?
345   ds = opts[:server] ? server(opts[:server]) : self
346   
347   if slice_size = opts.fetch(:commit_every, opts.fetch(:slice, default_import_slice))
348     offset = 0
349     rows = []
350     while offset < values.length
351       rows << ds._import(columns, values[offset, slice_size], opts)
352       offset += slice_size
353     end
354     rows.flatten
355   else
356     ds._import(columns, values, opts)
357   end
358 end
insert(*values, &block) click to toggle source

Inserts values into the associated table. The returned value is generally the value of the autoincremented primary key for the inserted row, assuming that a single row is inserted and the table has an autoincrementing primary key.

insert handles a number of different argument formats:

no arguments or single empty hash

Uses DEFAULT VALUES

single hash

Most common format, treats keys as columns and values as values

single array

Treats entries as values, with no columns

two arrays

Treats first array as columns, second array as values

single Dataset

Treats as an insert based on a selection from the dataset given, with no columns

array and dataset

Treats as an insert based on a selection from the dataset given, with the columns given by the array.

Examples:

DB[:items].insert
# INSERT INTO items DEFAULT VALUES

DB[:items].insert({})
# INSERT INTO items DEFAULT VALUES

DB[:items].insert([1,2,3])
# INSERT INTO items VALUES (1, 2, 3)

DB[:items].insert([:a, :b], [1,2])
# INSERT INTO items (a, b) VALUES (1, 2)

DB[:items].insert(a: 1, b: 2)
# INSERT INTO items (a, b) VALUES (1, 2)

DB[:items].insert(DB[:old_items])
# INSERT INTO items SELECT * FROM old_items

DB[:items].insert([:a, :b], DB[:old_items])
# INSERT INTO items (a, b) SELECT * FROM old_items
    # File lib/sequel/dataset/actions.rb
396 def insert(*values, &block)
397   sql = insert_sql(*values)
398   if uses_returning?(:insert)
399     returning_fetch_rows(sql, &block)
400   else
401     execute_insert(sql)
402   end
403 end
last(*args, &block) click to toggle source

Reverses the order and then runs first with the given arguments and block. Note that this will not necessarily give you the last record in the dataset, unless you have an unambiguous order. If there is not currently an order for this dataset, raises an Error.

DB[:table].order(:id).last # SELECT * FROM table ORDER BY id DESC LIMIT 1
# => {:id=>10}

DB[:table].order(Sequel.desc(:id)).last(2) # SELECT * FROM table ORDER BY id ASC LIMIT 2
# => [{:id=>1}, {:id=>2}]
    # File lib/sequel/dataset/actions.rb
415 def last(*args, &block)
416   raise(Error, 'No order specified') unless @opts[:order]
417   reverse.first(*args, &block)
418 end
map(column=nil, &block) click to toggle source

Maps column values for each record in the dataset (if an argument is given) or performs the stock mapping functionality of Enumerable otherwise. Raises an Error if both an argument and block are given.

DB[:table].map(:id) # SELECT * FROM table
# => [1, 2, 3, ...]

DB[:table].map{|r| r[:id] * 2} # SELECT * FROM table
# => [2, 4, 6, ...]

You can also provide an array of column names:

DB[:table].map([:id, :name]) # SELECT * FROM table
# => [[1, 'A'], [2, 'B'], [3, 'C'], ...]
Calls superclass method
    # File lib/sequel/dataset/actions.rb
434 def map(column=nil, &block)
435   if column
436     raise(Error, 'Must call Dataset#map with either an argument or a block, not both') if block
437     return naked.map(column) if row_proc
438     if column.is_a?(Array)
439       super(){|r| r.values_at(*column)}
440     else
441       super(){|r| r[column]}
442     end
443   else
444     super(&block)
445   end
446 end
max(arg=(no_arg = true), &block) click to toggle source

Returns the maximum value for the given column/expression. Uses a virtual row block if no argument is given.

DB[:table].max(:id) # SELECT max(id) FROM table LIMIT 1
# => 10
DB[:table].max{function(column)} # SELECT max(function(column)) FROM table LIMIT 1
# => 7
    # File lib/sequel/dataset/actions.rb
455 def max(arg=(no_arg = true), &block)
456   arg = Sequel.virtual_row(&block) if no_arg
457   _aggregate(:max, arg)
458 end
merge() click to toggle source

Execute a MERGE statement, which allows for INSERT, UPDATE, and DELETE behavior in a single query, based on whether rows from a source table match rows in the current table, based on the join conditions.

Unless the dataset uses static SQL, to use merge, you must first have called merge_using to specify the merge source and join conditions. You will then likely to call one or more of the following methods to specify MERGE behavior by adding WHEN [NOT] MATCHED clauses:

The WHEN [NOT] MATCHED clauses are added to the SQL in the order these methods were called on the dataset. If none of these methods are called, an error is raised.

Example:

DB[:m1]
  merge_using(:m2, i1: :i2).
  merge_insert(i1: :i2, a: Sequel[:b]+11).
  merge_delete{a > 30}.
  merge_update(i1: Sequel[:i1]+:i2+10, a: Sequel[:a]+:b+20).
  merge

SQL:

MERGE INTO m1 USING m2 ON (i1 = i2)
WHEN NOT MATCHED THEN INSERT (i1, a) VALUES (i2, (b + 11))
WHEN MATCHED AND (a > 30) THEN DELETE
WHEN MATCHED THEN UPDATE SET i1 = (i1 + i2 + 10), a = (a + b + 20)

On PostgreSQL, two additional merge methods are supported, for the PostgreSQL-specific DO NOTHING syntax.

  • merge_do_nothing_when_matched

  • merge_do_nothing_when_not_matched

This method is supported on Oracle, but Oracle's MERGE support is non-standard, and has the following issues:

  • DELETE clause requires UPDATE clause

  • DELETE clause requires a condition

  • DELETE clause only affects rows updated by UPDATE clause

    # File lib/sequel/dataset/actions.rb
505 def merge
506   execute_ddl(merge_sql)
507 end
min(arg=(no_arg = true), &block) click to toggle source

Returns the minimum value for the given column/expression. Uses a virtual row block if no argument is given.

DB[:table].min(:id) # SELECT min(id) FROM table LIMIT 1
# => 1
DB[:table].min{function(column)} # SELECT min(function(column)) FROM table LIMIT 1
# => 0
    # File lib/sequel/dataset/actions.rb
516 def min(arg=(no_arg = true), &block)
517   arg = Sequel.virtual_row(&block) if no_arg
518   _aggregate(:min, arg)
519 end
multi_insert(hashes, opts=OPTS) click to toggle source

This is a front end for import that allows you to submit an array of hashes instead of arrays of columns and values:

DB[:table].multi_insert([{x: 1}, {x: 2}])
# INSERT INTO table (x) VALUES (1)
# INSERT INTO table (x) VALUES (2)

Be aware that all hashes should have the same keys if you use this calling method, otherwise some columns could be missed or set to null instead of to default values.

This respects the same options as import.

    # File lib/sequel/dataset/actions.rb
533 def multi_insert(hashes, opts=OPTS)
534   return if hashes.empty?
535   columns = hashes.first.keys
536   import(columns, hashes.map{|h| columns.map{|c| h[c]}}, opts)
537 end
paged_each(opts=OPTS) { || ... } click to toggle source

Yields each row in the dataset, but internally uses multiple queries as needed to process the entire result set without keeping all rows in the dataset in memory, even if the underlying driver buffers all query results in memory.

Because this uses multiple queries internally, in order to remain consistent, it also uses a transaction internally. Additionally, to work correctly, the dataset must have unambiguous order. Using an ambiguous order can result in an infinite loop, as well as subtler bugs such as yielding duplicate rows or rows being skipped.

Sequel checks that the datasets using this method have an order, but it cannot ensure that the order is unambiguous.

Note that this method is not safe to use on many adapters if you are running additional queries inside the provided block. If you are running queries inside the block, use a separate thread or shard inside paged_each.

Options:

:rows_per_fetch

The number of rows to fetch per query. Defaults to 1000.

:strategy

The strategy to use for paging of results. By default this is :offset, for using an approach with a limit and offset for every page. This can be set to :filter, which uses a limit and a filter that excludes rows from previous pages. In order for this strategy to work, you must be selecting the columns you are ordering by, and none of the columns can contain NULLs. Note that some Sequel adapters have optimized implementations that will use cursors or streaming regardless of the :strategy option used.

:filter_values

If the strategy: :filter option is used, this option should be a proc that accepts the last retrieved row for the previous page and an array of ORDER BY expressions, and returns an array of values relating to those expressions for the last retrieved row. You will need to use this option if your ORDER BY expressions are not simple columns, if they contain qualified identifiers that would be ambiguous unqualified, if they contain any identifiers that are aliased in SELECT, and potentially other cases.

Examples:

DB[:table].order(:id).paged_each{|row| }
# SELECT * FROM table ORDER BY id LIMIT 1000
# SELECT * FROM table ORDER BY id LIMIT 1000 OFFSET 1000
# ...

DB[:table].order(:id).paged_each(:rows_per_fetch=>100){|row| }
# SELECT * FROM table ORDER BY id LIMIT 100
# SELECT * FROM table ORDER BY id LIMIT 100 OFFSET 100
# ...

DB[:table].order(:id).paged_each(strategy: :filter){|row| }
# SELECT * FROM table ORDER BY id LIMIT 1000
# SELECT * FROM table WHERE id > 1001 ORDER BY id LIMIT 1000
# ...

DB[:table].order(:id).paged_each(strategy: :filter,
  filter_values: lambda{|row, exprs| [row[:id]]}){|row| }
# SELECT * FROM table ORDER BY id LIMIT 1000
# SELECT * FROM table WHERE id > 1001 ORDER BY id LIMIT 1000
# ...
    # File lib/sequel/dataset/actions.rb
594 def paged_each(opts=OPTS)
595   unless @opts[:order]
596     raise Sequel::Error, "Dataset#paged_each requires the dataset be ordered"
597   end
598   unless defined?(yield)
599     return enum_for(:paged_each, opts)
600   end
601 
602   total_limit = @opts[:limit]
603   offset = @opts[:offset]
604   if server = @opts[:server]
605     opts = Hash[opts]
606     opts[:server] = server
607   end
608 
609   rows_per_fetch = opts[:rows_per_fetch] || 1000
610   strategy = if offset || total_limit
611     :offset
612   else
613     opts[:strategy] || :offset
614   end
615 
616   db.transaction(opts) do
617     case strategy
618     when :filter
619       filter_values = opts[:filter_values] || proc{|row, exprs| exprs.map{|e| row[hash_key_symbol(e)]}}
620       base_ds = ds = limit(rows_per_fetch)
621       while ds
622         last_row = nil
623         ds.each do |row|
624           last_row = row
625           yield row
626         end
627         ds = (base_ds.where(ignore_values_preceding(last_row, &filter_values)) if last_row)
628       end
629     else
630       offset ||= 0
631       num_rows_yielded = rows_per_fetch
632       total_rows = 0
633 
634       while num_rows_yielded == rows_per_fetch && (total_limit.nil? || total_rows < total_limit)
635         if total_limit && total_rows + rows_per_fetch > total_limit
636           rows_per_fetch = total_limit - total_rows
637         end
638 
639         num_rows_yielded = 0
640         limit(rows_per_fetch, offset).each do |row|
641           num_rows_yielded += 1
642           total_rows += 1 if total_limit
643           yield row
644         end
645 
646         offset += rows_per_fetch
647       end
648     end
649   end
650 
651   self
652 end
select_hash(key_column, value_column, opts = OPTS) click to toggle source

Returns a hash with key_column values as keys and value_column values as values. Similar to as_hash, but only selects the columns given. Like as_hash, it accepts an optional :hash parameter, into which entries will be merged.

DB[:table].select_hash(:id, :name)
# SELECT id, name FROM table
# => {1=>'a', 2=>'b', ...}

You can also provide an array of column names for either the key_column, the value column, or both:

DB[:table].select_hash([:id, :foo], [:name, :bar])
# SELECT id, foo, name, bar FROM table
# => {[1, 3]=>['a', 'c'], [2, 4]=>['b', 'd'], ...}

When using this method, you must be sure that each expression has an alias that Sequel can determine.

    # File lib/sequel/dataset/actions.rb
672 def select_hash(key_column, value_column, opts = OPTS)
673   _select_hash(:as_hash, key_column, value_column, opts)
674 end
select_hash_groups(key_column, value_column, opts = OPTS) click to toggle source

Returns a hash with key_column values as keys and an array of value_column values. Similar to to_hash_groups, but only selects the columns given. Like to_hash_groups, it accepts an optional :hash parameter, into which entries will be merged.

DB[:table].select_hash_groups(:name, :id)
# SELECT id, name FROM table
# => {'a'=>[1, 4, ...], 'b'=>[2, ...], ...}

You can also provide an array of column names for either the key_column, the value column, or both:

DB[:table].select_hash_groups([:first, :middle], [:last, :id])
# SELECT first, middle, last, id FROM table
# => {['a', 'b']=>[['c', 1], ['d', 2], ...], ...}

When using this method, you must be sure that each expression has an alias that Sequel can determine.

    # File lib/sequel/dataset/actions.rb
693 def select_hash_groups(key_column, value_column, opts = OPTS)
694   _select_hash(:to_hash_groups, key_column, value_column, opts)
695 end
select_map(column=nil, &block) click to toggle source

Selects the column given (either as an argument or as a block), and returns an array of all values of that column in the dataset. If you give a block argument that returns an array with multiple entries, the contents of the resulting array are undefined. Raises an Error if called with both an argument and a block.

DB[:table].select_map(:id) # SELECT id FROM table
# => [3, 5, 8, 1, ...]

DB[:table].select_map{id * 2} # SELECT (id * 2) FROM table
# => [6, 10, 16, 2, ...]

You can also provide an array of column names:

DB[:table].select_map([:id, :name]) # SELECT id, name FROM table
# => [[1, 'A'], [2, 'B'], [3, 'C'], ...]

If you provide an array of expressions, you must be sure that each entry in the array has an alias that Sequel can determine.

    # File lib/sequel/dataset/actions.rb
716 def select_map(column=nil, &block)
717   _select_map(column, false, &block)
718 end
select_order_map(column=nil, &block) click to toggle source

The same as select_map, but in addition orders the array by the column.

DB[:table].select_order_map(:id) # SELECT id FROM table ORDER BY id
# => [1, 2, 3, 4, ...]

DB[:table].select_order_map{id * 2} # SELECT (id * 2) FROM table ORDER BY (id * 2)
# => [2, 4, 6, 8, ...]

You can also provide an array of column names:

DB[:table].select_order_map([:id, :name]) # SELECT id, name FROM table ORDER BY id, name
# => [[1, 'A'], [2, 'B'], [3, 'C'], ...]

If you provide an array of expressions, you must be sure that each entry in the array has an alias that Sequel can determine.

    # File lib/sequel/dataset/actions.rb
735 def select_order_map(column=nil, &block)
736   _select_map(column, true, &block)
737 end
single_record() click to toggle source

Limits the dataset to one record, and returns the first record in the dataset, or nil if the dataset has no records. Users should probably use first instead of this method. Example:

DB[:test].single_record # SELECT * FROM test LIMIT 1
# => {:column_name=>'value'}
    # File lib/sequel/dataset/actions.rb
745 def single_record
746   _single_record_ds.single_record!
747 end
single_record!() click to toggle source

Returns the first record in dataset, without limiting the dataset. Returns nil if the dataset has no records. Users should probably use first instead of this method. This should only be used if you know the dataset is already limited to a single record. This method may be desirable to use for performance reasons, as it does not clone the receiver. Example:

DB[:test].single_record! # SELECT * FROM test
# => {:column_name=>'value'}
    # File lib/sequel/dataset/actions.rb
757 def single_record!
758   with_sql_first(select_sql)
759 end
single_value() click to toggle source

Returns the first value of the first record in the dataset. Returns nil if dataset is empty. Users should generally use get instead of this method. Example:

DB[:test].single_value # SELECT * FROM test LIMIT 1
# => 'value'
    # File lib/sequel/dataset/actions.rb
767 def single_value
768   single_value_ds.each do |r|
769     r.each{|_, v| return v}
770   end
771   nil
772 end
single_value!() click to toggle source

Returns the first value of the first record in the dataset, without limiting the dataset. Returns nil if the dataset is empty. Users should generally use get instead of this method. Should not be used on graphed datasets or datasets that have row_procs that don't return hashes. This method may be desirable to use for performance reasons, as it does not clone the receiver.

DB[:test].single_value! # SELECT * FROM test
# => 'value'
    # File lib/sequel/dataset/actions.rb
782 def single_value!
783   with_sql_single_value(select_sql)
784 end
sum(arg=(no_arg = true), &block) click to toggle source

Returns the sum for the given column/expression. Uses a virtual row block if no column is given.

DB[:table].sum(:id) # SELECT sum(id) FROM table LIMIT 1
# => 55
DB[:table].sum{function(column)} # SELECT sum(function(column)) FROM table LIMIT 1
# => 10
    # File lib/sequel/dataset/actions.rb
793 def sum(arg=(no_arg = true), &block)
794   arg = Sequel.virtual_row(&block) if no_arg
795   _aggregate(:sum, arg)
796 end
to_hash(*a) click to toggle source

Alias of as_hash for backwards compatibility.

    # File lib/sequel/dataset/actions.rb
850 def to_hash(*a)
851   as_hash(*a)
852 end
to_hash_groups(key_column, value_column = nil, opts = OPTS) click to toggle source

Returns a hash with one column used as key and the values being an array of column values. If the value_column is not given or nil, uses the entire hash as the value.

DB[:table].to_hash_groups(:name, :id) # SELECT * FROM table
# {'Jim'=>[1, 4, 16, ...], 'Bob'=>[2], ...}

DB[:table].to_hash_groups(:name) # SELECT * FROM table
# {'Jim'=>[{:id=>1, :name=>'Jim'}, {:id=>4, :name=>'Jim'}, ...], 'Bob'=>[{:id=>2, :name=>'Bob'}], ...}

You can also provide an array of column names for either the key_column, the value column, or both:

DB[:table].to_hash_groups([:first, :middle], [:last, :id]) # SELECT * FROM table
# {['Jim', 'Bob']=>[['Smith', 1], ['Jackson', 4], ...], ...}

DB[:table].to_hash_groups([:first, :middle]) # SELECT * FROM table
# {['Jim', 'Bob']=>[{:id=>1, :first=>'Jim', :middle=>'Bob', :last=>'Smith'}, ...], ...}

Options:

:all

Use all instead of each to retrieve the objects

:hash

The object into which the values will be placed. If this is not given, an empty hash is used. This can be used to use a hash with a default value or default proc.

    # File lib/sequel/dataset/actions.rb
878 def to_hash_groups(key_column, value_column = nil, opts = OPTS)
879   h = opts[:hash] || {}
880   meth = opts[:all] ? :all : :each
881   if value_column
882     return naked.to_hash_groups(key_column, value_column, opts) if row_proc
883     if value_column.is_a?(Array)
884       if key_column.is_a?(Array)
885         public_send(meth){|r| (h[r.values_at(*key_column)] ||= []) << r.values_at(*value_column)}
886       else
887         public_send(meth){|r| (h[r[key_column]] ||= []) << r.values_at(*value_column)}
888       end
889     else
890       if key_column.is_a?(Array)
891         public_send(meth){|r| (h[r.values_at(*key_column)] ||= []) << r[value_column]}
892       else
893         public_send(meth){|r| (h[r[key_column]] ||= []) << r[value_column]}
894       end
895     end
896   elsif key_column.is_a?(Array)
897     public_send(meth){|r| (h[key_column.map{|k| r[k]}] ||= []) << r}
898   else
899     public_send(meth){|r| (h[r[key_column]] ||= []) << r}
900   end
901   h
902 end
truncate() click to toggle source

Truncates the dataset. Returns nil.

DB[:table].truncate # TRUNCATE table
# => nil
    # File lib/sequel/dataset/actions.rb
908 def truncate
909   execute_ddl(truncate_sql)
910 end
update(values=OPTS, &block) click to toggle source

Updates values for the dataset. The returned value is the number of rows updated. values should be a hash where the keys are columns to set and values are the values to which to set the columns.

DB[:table].update(x: nil) # UPDATE table SET x = NULL
# => 10

DB[:table].update(x: Sequel[:x]+1, y: 0) # UPDATE table SET x = (x + 1), y = 0
# => 10
    # File lib/sequel/dataset/actions.rb
921 def update(values=OPTS, &block)
922   sql = update_sql(values)
923   if uses_returning?(:update)
924     returning_fetch_rows(sql, &block)
925   else
926     execute_dui(sql)
927   end
928 end
where_all(cond, &block) click to toggle source

Return an array of all rows matching the given filter condition, also yielding each row to the given block. Basically the same as where(cond).all(&block), except it can be optimized to not create an intermediate dataset.

DB[:table].where_all(id: [1,2,3])
# SELECT * FROM table WHERE (id IN (1, 2, 3))
    # File lib/sequel/dataset/actions.rb
936 def where_all(cond, &block)
937   if loader = _where_loader([cond], nil)
938     loader.all(filter_expr(cond), &block)
939   else
940     where(cond).all(&block)
941   end
942 end
where_each(cond, &block) click to toggle source

Iterate over all rows matching the given filter condition, yielding each row to the given block. Basically the same as where(cond).each(&block), except it can be optimized to not create an intermediate dataset.

DB[:table].where_each(id: [1,2,3]){|row| p row}
# SELECT * FROM table WHERE (id IN (1, 2, 3))
    # File lib/sequel/dataset/actions.rb
950 def where_each(cond, &block)
951   if loader = _where_loader([cond], nil)
952     loader.each(filter_expr(cond), &block)
953   else
954     where(cond).each(&block)
955   end
956 end
where_single_value(cond) click to toggle source

Filter the datasets using the given filter condition, then return a single value. This assumes that the dataset has already been setup to limit the selection to a single column. Basically the same as where(cond).single_value, except it can be optimized to not create an intermediate dataset.

DB[:table].select(:name).where_single_value(id: 1)
# SELECT name FROM table WHERE (id = 1) LIMIT 1
    # File lib/sequel/dataset/actions.rb
965 def where_single_value(cond)
966   if loader = cached_where_placeholder_literalizer([cond], nil, :_where_single_value_loader) do |pl|
967       single_value_ds.where(pl.arg)
968     end
969 
970     loader.get(filter_expr(cond))
971   else
972     where(cond).single_value
973   end
974 end
with_sql_all(sql, &block) click to toggle source

Run the given SQL and return an array of all rows. If a block is given, each row is yielded to the block after all rows are loaded. See with_sql_each.

    # File lib/sequel/dataset/actions.rb
978 def with_sql_all(sql, &block)
979   _all(block){|a| with_sql_each(sql){|r| a << r}}
980 end
with_sql_delete(sql) click to toggle source

Execute the given SQL and return the number of rows deleted. This exists solely as an optimization, replacing with_sql(sql).delete. It's significantly faster as it does not require cloning the current dataset.

    # File lib/sequel/dataset/actions.rb
985 def with_sql_delete(sql)
986   execute_dui(sql)
987 end
Also aliased as: with_sql_update
with_sql_each(sql) { |call| ... } click to toggle source

Run the given SQL and yield each returned row to the block.

    # File lib/sequel/dataset/actions.rb
991 def with_sql_each(sql)
992   if rp = row_proc
993     _with_sql_dataset.fetch_rows(sql){|r| yield rp.call(r)}
994   else
995     _with_sql_dataset.fetch_rows(sql){|r| yield r}
996   end
997   self
998 end
with_sql_first(sql) click to toggle source

Run the given SQL and return the first row, or nil if no rows were returned. See with_sql_each.

     # File lib/sequel/dataset/actions.rb
1002 def with_sql_first(sql)
1003   with_sql_each(sql){|r| return r}
1004   nil
1005 end
with_sql_insert(sql) click to toggle source

Execute the given SQL and (on most databases) return the primary key of the inserted row.

     # File lib/sequel/dataset/actions.rb
1018 def with_sql_insert(sql)
1019   execute_insert(sql)
1020 end
with_sql_single_value(sql) click to toggle source

Run the given SQL and return the first value in the first row, or nil if no rows were returned. For this to make sense, the SQL given should select only a single value. See with_sql_each.

     # File lib/sequel/dataset/actions.rb
1010 def with_sql_single_value(sql)
1011   if r = with_sql_first(sql)
1012     r.each{|_, v| return v}
1013   end
1014 end
with_sql_update(sql)
Alias for: with_sql_delete

Protected Instance Methods

_import(columns, values, opts) click to toggle source

Internals of import. If primary key values are requested, use separate insert commands for each row. Otherwise, call multi_insert_sql and execute each statement it gives separately.

     # File lib/sequel/dataset/actions.rb
1027 def _import(columns, values, opts)
1028   trans_opts = Hash[opts]
1029   trans_opts[:server] = @opts[:server]
1030   if opts[:return] == :primary_key
1031     @db.transaction(trans_opts){values.map{|v| insert(columns, v)}}
1032   else
1033     stmts = multi_insert_sql(columns, values)
1034     @db.transaction(trans_opts){stmts.each{|st| execute_dui(st)}}
1035   end
1036 end
_select_map_multiple(ret_cols) click to toggle source

Return an array of arrays of values given by the symbols in ret_cols.

     # File lib/sequel/dataset/actions.rb
1039 def _select_map_multiple(ret_cols)
1040   map{|r| r.values_at(*ret_cols)}
1041 end
_select_map_single() click to toggle source

Returns an array of the first value in each row.

     # File lib/sequel/dataset/actions.rb
1044 def _select_map_single
1045   k = nil
1046   map{|r| r[k||=r.keys.first]}
1047 end
single_value_ds() click to toggle source

A dataset for returning single values from the current dataset.

     # File lib/sequel/dataset/actions.rb
1050 def single_value_ds
1051   clone(:limit=>1).ungraphed.naked
1052 end

Private Instance Methods

_aggregate(function, arg) click to toggle source

Cached placeholder literalizer for methods that return values using aggregate functions.

     # File lib/sequel/dataset/actions.rb
1066 def _aggregate(function, arg)
1067   if loader = cached_placeholder_literalizer(:"_#{function}_loader") do |pl|
1068         aggregate_dataset.limit(1).select(SQL::Function.new(function, pl.arg).as(function))
1069       end
1070     loader.get(arg)
1071   else
1072     aggregate_dataset.get(SQL::Function.new(function, arg).as(function))
1073   end
1074 end
_all(block) { |a| ... } click to toggle source

Internals of all and with_sql_all

     # File lib/sequel/dataset/actions.rb
1057 def _all(block)
1058   a = []
1059   yield a
1060   post_load(a)
1061   a.each(&block) if block
1062   a
1063 end
_hash_key_symbol(s, recursing=false) click to toggle source

Return a plain symbol given a potentially qualified or aliased symbol, specifying the symbol that is likely to be used as the hash key for the column when records are returned. Return nil if no hash key can be determined

     # File lib/sequel/dataset/actions.rb
1165 def _hash_key_symbol(s, recursing=false)
1166   case s
1167   when Symbol
1168     _, c, a = split_symbol(s)
1169     (a || c).to_sym
1170   when SQL::Identifier, SQL::Wrapper
1171     _hash_key_symbol(s.value, true)
1172   when SQL::QualifiedIdentifier
1173     _hash_key_symbol(s.column, true)
1174   when SQL::AliasedExpression
1175     _hash_key_symbol(s.alias, true)
1176   when String
1177     s.to_sym if recursing
1178   end
1179 end
_select_hash(meth, key_column, value_column, opts=OPTS) click to toggle source

Internals of select_hash and select_hash_groups

     # File lib/sequel/dataset/actions.rb
1077 def _select_hash(meth, key_column, value_column, opts=OPTS)
1078   select(*(key_column.is_a?(Array) ? key_column : [key_column]) + (value_column.is_a?(Array) ? value_column : [value_column])).
1079     public_send(meth, hash_key_symbols(key_column), hash_key_symbols(value_column), opts)
1080 end
_select_map(column, order, &block) click to toggle source

Internals of select_map and select_order_map

     # File lib/sequel/dataset/actions.rb
1083 def _select_map(column, order, &block)
1084   ds = ungraphed.naked
1085   columns = Array(column)
1086   virtual_row_columns(columns, block)
1087   select_cols = order ? columns.map{|c| c.is_a?(SQL::OrderedExpression) ? c.expression : c} : columns
1088   ds = ds.order(*columns.map{|c| unaliased_identifier(c)}) if order
1089   if column.is_a?(Array) || (columns.length > 1)
1090     ds.select(*select_cols)._select_map_multiple(hash_key_symbols(select_cols))
1091   else
1092     ds.select(auto_alias_expression(select_cols.first))._select_map_single
1093   end
1094 end
_single_record_ds() click to toggle source

A cached dataset for a single record for this dataset.

     # File lib/sequel/dataset/actions.rb
1097 def _single_record_ds
1098   cached_dataset(:_single_record_ds){clone(:limit=>1)}
1099 end
_where_loader(where_args, where_block) click to toggle source

Loader used for where_all and where_each.

     # File lib/sequel/dataset/actions.rb
1102 def _where_loader(where_args, where_block)
1103   cached_where_placeholder_literalizer(where_args, where_block, :_where_loader) do |pl|
1104     where(pl.arg)
1105   end
1106 end
_with_sql_dataset() click to toggle source

Cached dataset to use for with_sql_#{all,each,first,single_value}. This is used so that the columns returned by the given SQL do not affect the receiver of the with_sql_* method.

     # File lib/sequel/dataset/actions.rb
1283 def _with_sql_dataset
1284   if @opts[:_with_sql_ds]
1285     self
1286   else
1287     cached_dataset(:_with_sql_ds) do
1288       clone(:_with_sql_ds=>true)
1289     end
1290   end
1291 end
auto_alias_expression(v) click to toggle source

Automatically alias the given expression if it does not have an identifiable alias.

     # File lib/sequel/dataset/actions.rb
1109 def auto_alias_expression(v)
1110   case v
1111   when LiteralString, Symbol, SQL::Identifier, SQL::QualifiedIdentifier, SQL::AliasedExpression
1112     v
1113   else
1114     SQL::AliasedExpression.new(v, :v)
1115   end
1116 end
default_import_slice() click to toggle source

The default number of rows that can be inserted in a single INSERT statement via import. The default is for no limit.

     # File lib/sequel/dataset/actions.rb
1120 def default_import_slice
1121   nil
1122 end
default_server_opts(opts) click to toggle source

Set the server to use to :default unless it is already set in the passed opts

     # File lib/sequel/dataset/actions.rb
1125 def default_server_opts(opts)
1126   if @db.sharded? && !opts.has_key?(:server)
1127     opts = Hash[opts]
1128     opts[:server] = @opts[:server] || :default
1129   end
1130   opts
1131 end
execute(sql, opts=OPTS, &block) click to toggle source

Execute the given select SQL on the database using execute. Use the :read_only server unless a specific server is set.

     # File lib/sequel/dataset/actions.rb
1135 def execute(sql, opts=OPTS, &block)
1136   db = @db
1137   if db.sharded? && !opts.has_key?(:server)
1138     opts = Hash[opts]
1139     opts[:server] = @opts[:server] || (@opts[:lock] ? :default : :read_only)
1140     opts
1141   end
1142   db.execute(sql, opts, &block)
1143 end
execute_ddl(sql, opts=OPTS, &block) click to toggle source

Execute the given SQL on the database using execute_ddl.

     # File lib/sequel/dataset/actions.rb
1146 def execute_ddl(sql, opts=OPTS, &block)
1147   @db.execute_ddl(sql, default_server_opts(opts), &block)
1148   nil
1149 end
execute_dui(sql, opts=OPTS, &block) click to toggle source

Execute the given SQL on the database using execute_dui.

     # File lib/sequel/dataset/actions.rb
1152 def execute_dui(sql, opts=OPTS, &block)
1153   @db.execute_dui(sql, default_server_opts(opts), &block)
1154 end
execute_insert(sql, opts=OPTS, &block) click to toggle source

Execute the given SQL on the database using execute_insert.

     # File lib/sequel/dataset/actions.rb
1157 def execute_insert(sql, opts=OPTS, &block)
1158   @db.execute_insert(sql, default_server_opts(opts), &block)
1159 end
hash_key_symbol(s) click to toggle source

Return a plain symbol given a potentially qualified or aliased symbol, specifying the symbol that is likely to be used as the hash key for the column when records are returned. Raise Error if the hash key symbol cannot be returned.

     # File lib/sequel/dataset/actions.rb
1185 def hash_key_symbol(s)
1186   if v = _hash_key_symbol(s)
1187     v
1188   else
1189     raise(Error, "#{s.inspect} is not supported, should be a Symbol, SQL::Identifier, SQL::QualifiedIdentifier, or SQL::AliasedExpression")
1190   end
1191 end
hash_key_symbols(s) click to toggle source

If s is an array, return an array with the given hash key symbols. Otherwise, return a hash key symbol for the given expression If a hash key symbol cannot be determined, raise an error.

     # File lib/sequel/dataset/actions.rb
1196 def hash_key_symbols(s)
1197   s.is_a?(Array) ? s.map{|c| hash_key_symbol(c)} : hash_key_symbol(s)
1198 end
ignore_values_preceding(row) { |row, map(&:first)| ... } click to toggle source

Returns an expression that will ignore values preceding the given row, using the receiver's current order. This yields the row and the array of order expressions to the block, which should return an array of values to use.

     # File lib/sequel/dataset/actions.rb
1203 def ignore_values_preceding(row)
1204   @opts[:order].map{|v| v.is_a?(SQL::OrderedExpression) ? v.expression : v}
1205 
1206   order_exprs = @opts[:order].map do |v|
1207     if v.is_a?(SQL::OrderedExpression)
1208       descending = v.descending
1209       v = v.expression
1210     else
1211       descending = false
1212     end
1213     [v, descending]
1214   end
1215 
1216   row_values = yield(row, order_exprs.map(&:first))
1217 
1218   last_expr = []
1219   cond = order_exprs.zip(row_values).map do |(v, descending), value|
1220     expr =  last_expr + [SQL::BooleanExpression.new(descending ? :< : :>, v, value)]
1221     last_expr += [SQL::BooleanExpression.new(:'=', v, value)]
1222     Sequel.&(*expr)
1223   end
1224   Sequel.|(*cond)
1225 end
output_identifier(v) click to toggle source

Downcase identifiers by default when outputing them from the database.

     # File lib/sequel/dataset/actions.rb
1228 def output_identifier(v)
1229   v = 'untitled' if v == ''
1230   v.to_s.downcase.to_sym
1231 end
post_load(all_records) click to toggle source

This is run inside .all, after all of the records have been loaded via .each, but before any block passed to all is called. It is called with a single argument, an array of all returned records. Does nothing by default, added to make the model eager loading code simpler.

     # File lib/sequel/dataset/actions.rb
1237 def post_load(all_records)
1238 end
returning_fetch_rows(sql, &block) click to toggle source

Called by insert/update/delete when returning is used. Yields each row as a plain hash to the block if one is given, or returns an array of plain hashes for all rows if a block is not given

     # File lib/sequel/dataset/actions.rb
1243 def returning_fetch_rows(sql, &block)
1244   if block
1245     default_server.fetch_rows(sql, &block)
1246     nil
1247   else
1248     rows = []
1249     default_server.fetch_rows(sql){|r| rows << r}
1250     rows
1251   end
1252 end
unaliased_identifier(c) click to toggle source

Return the unaliased part of the identifier. Handles both implicit aliases in symbols, as well as SQL::AliasedExpression objects. Other objects are returned as is.

     # File lib/sequel/dataset/actions.rb
1257 def unaliased_identifier(c)
1258   case c
1259   when Symbol
1260     table, column, aliaz = split_symbol(c)
1261     if aliaz
1262       table ? SQL::QualifiedIdentifier.new(table, column) : Sequel.identifier(column)
1263     else
1264       c
1265     end
1266   when SQL::AliasedExpression
1267     c.expression
1268   when SQL::OrderedExpression
1269     case expr = c.expression
1270     when Symbol, SQL::AliasedExpression
1271       SQL::OrderedExpression.new(unaliased_identifier(expr), c.descending, :nulls=>c.nulls)
1272     else
1273       c
1274     end
1275   else
1276     c
1277   end
1278 end

3 - User Methods relating to SQL Creation

↑ top

Public Instance Methods

exists() click to toggle source

Returns an EXISTS clause for the dataset as an SQL::PlaceholderLiteralString.

DB.select(1).where(DB[:items].exists)
# SELECT 1 WHERE (EXISTS (SELECT * FROM items))
   # File lib/sequel/dataset/sql.rb
14 def exists
15   SQL::PlaceholderLiteralString.new(EXISTS, [self], true)
16 end
insert_sql(*values) click to toggle source

Returns an INSERT SQL query string. See insert.

DB[:items].insert_sql(a: 1)
# => "INSERT INTO items (a) VALUES (1)"
   # File lib/sequel/dataset/sql.rb
22 def insert_sql(*values)
23   return static_sql(@opts[:sql]) if @opts[:sql]
24 
25   check_insert_allowed!
26 
27   columns, values = _parse_insert_sql_args(values)
28   if values.is_a?(Array) && values.empty? && !insert_supports_empty_values? 
29     columns, values = insert_empty_columns_values
30   elsif values.is_a?(Dataset) && hoist_cte?(values) && supports_cte?(:insert)
31     ds, values = hoist_cte(values)
32     return ds.clone(:columns=>columns, :values=>values).send(:_insert_sql)
33   end
34   clone(:columns=>columns, :values=>values).send(:_insert_sql)
35 end
literal_append(sql, v) click to toggle source

Append a literal representation of a value to the given SQL string.

If an unsupported object is given, an Error is raised.

   # File lib/sequel/dataset/sql.rb
40 def literal_append(sql, v)
41   case v
42   when Symbol
43     if skip_symbol_cache?
44       literal_symbol_append(sql, v)
45     else 
46       unless l = db.literal_symbol(v)
47         l = String.new
48         literal_symbol_append(l, v)
49         db.literal_symbol_set(v, l)
50       end
51       sql << l
52     end
53   when String
54     case v
55     when LiteralString
56       sql << v
57     when SQL::Blob
58       literal_blob_append(sql, v)
59     else
60       literal_string_append(sql, v)
61     end
62   when Integer
63     sql << literal_integer(v)
64   when Hash
65     literal_hash_append(sql, v)
66   when SQL::Expression
67     literal_expression_append(sql, v)
68   when Float
69     sql << literal_float(v)
70   when BigDecimal
71     sql << literal_big_decimal(v)
72   when NilClass
73     sql << literal_nil
74   when TrueClass
75     sql << literal_true
76   when FalseClass
77     sql << literal_false
78   when Array
79     literal_array_append(sql, v)
80   when Time
81     v.is_a?(SQLTime) ? literal_sqltime_append(sql, v) : literal_time_append(sql, v)
82   when DateTime
83     literal_datetime_append(sql, v)
84   when Date
85     sql << literal_date(v)
86   when Dataset
87     literal_dataset_append(sql, v)
88   else
89     literal_other_append(sql, v)
90   end
91 end
merge_sql() click to toggle source

The SQL to use for the MERGE statement.

    # File lib/sequel/dataset/sql.rb
 94 def merge_sql
 95   raise Error, "This database doesn't support MERGE" unless supports_merge?
 96   if sql = opts[:sql]
 97     return static_sql(sql)
 98   end
 99   if sql = cache_get(:_merge_sql)
100     return sql
101   end
102   source, join_condition = @opts[:merge_using]
103   raise Error, "No USING clause for MERGE" unless source
104   sql = @opts[:append_sql] || sql_string_origin
105 
106   select_with_sql(sql)
107   sql << "MERGE INTO "
108   source_list_append(sql, @opts[:from])
109   sql << " USING "
110   identifier_append(sql, source)
111   sql << " ON "
112   literal_append(sql, join_condition)
113   _merge_when_sql(sql)
114   cache_set(:_merge_sql, sql) if cache_sql?
115   sql
116 end
multi_insert_sql(columns, values) click to toggle source

Returns an array of insert statements for inserting multiple records. This method is used by multi_insert to format insert statements and expects a keys array and and an array of value arrays.

    # File lib/sequel/dataset/sql.rb
121 def multi_insert_sql(columns, values)
122   case multi_insert_sql_strategy
123   when :values
124     sql = LiteralString.new('VALUES ')
125     expression_list_append(sql, values.map{|r| Array(r)})
126     [insert_sql(columns, sql)]
127   when :union
128     c = false
129     sql = LiteralString.new
130     u = ' UNION ALL SELECT '
131     f = empty_from_sql
132     values.each do |v|
133       if c
134         sql << u
135       else
136         sql << 'SELECT '
137         c = true
138       end
139       expression_list_append(sql, v)
140       sql << f if f
141     end
142     [insert_sql(columns, sql)]
143   else
144     values.map{|r| insert_sql(columns, r)}
145   end
146 end
sql() click to toggle source

Same as select_sql, not aliased directly to make subclassing simpler.

    # File lib/sequel/dataset/sql.rb
149 def sql
150   select_sql
151 end
truncate_sql() click to toggle source

Returns a TRUNCATE SQL query string. See truncate

DB[:items].truncate_sql # => 'TRUNCATE items'
    # File lib/sequel/dataset/sql.rb
156 def truncate_sql
157   if opts[:sql]
158     static_sql(opts[:sql])
159   else
160     check_truncation_allowed!
161     check_not_limited!(:truncate)
162     raise(InvalidOperation, "Can't truncate filtered datasets") if opts[:where] || opts[:having]
163     t = String.new
164     source_list_append(t, opts[:from])
165     _truncate_sql(t)
166   end
167 end
update_sql(values = OPTS) click to toggle source

Formats an UPDATE statement using the given values. See update.

DB[:items].update_sql(price: 100, category: 'software')
# => "UPDATE items SET price = 100, category = 'software'

Raises an Error if the dataset is grouped or includes more than one table.

    # File lib/sequel/dataset/sql.rb
176 def update_sql(values = OPTS)
177   return static_sql(opts[:sql]) if opts[:sql]
178   check_update_allowed!
179   check_not_limited!(:update)
180 
181   case values
182   when LiteralString
183     # nothing
184   when String
185     raise Error, "plain string passed to Dataset#update is not supported, use Sequel.lit to use a literal string"
186   end
187 
188   clone(:values=>values).send(:_update_sql)
189 end

4 - Methods that describe what the dataset supports

↑ top

Public Instance Methods

provides_accurate_rows_matched?() click to toggle source

Whether this dataset will provide accurate number of rows matched for delete and update statements, true by default. Accurate in this case is the number of rows matched by the dataset's filter.

   # File lib/sequel/dataset/features.rb
19 def provides_accurate_rows_matched?
20   true
21 end
quote_identifiers?() click to toggle source

Whether this dataset quotes identifiers.

   # File lib/sequel/dataset/features.rb
12 def quote_identifiers?
13   @opts.fetch(:quote_identifiers, true)
14 end
recursive_cte_requires_column_aliases?() click to toggle source

Whether you must use a column alias list for recursive CTEs, false by default.

   # File lib/sequel/dataset/features.rb
24 def recursive_cte_requires_column_aliases?
25   false
26 end
requires_placeholder_type_specifiers?() click to toggle source

Whether type specifiers are required for prepared statement/bound variable argument placeholders (i.e. :bv__integer), false by default.

   # File lib/sequel/dataset/features.rb
36 def requires_placeholder_type_specifiers?
37   false
38 end
requires_sql_standard_datetimes?() click to toggle source

Whether the dataset requires SQL standard datetimes. False by default, as most allow strings with ISO 8601 format.

   # File lib/sequel/dataset/features.rb
30 def requires_sql_standard_datetimes?
31   false
32 end
supports_cte?(type=:select) click to toggle source

Whether the dataset supports common table expressions, false by default. If given, type can be :select, :insert, :update, or :delete, in which case it determines whether WITH is supported for the respective statement type.

   # File lib/sequel/dataset/features.rb
43 def supports_cte?(type=:select)
44   false
45 end
supports_cte_in_subqueries?() click to toggle source

Whether the dataset supports common table expressions in subqueries, false by default. If false, applies the WITH clause to the main query, which can cause issues if multiple WITH clauses use the same name.

   # File lib/sequel/dataset/features.rb
50 def supports_cte_in_subqueries?
51   false
52 end
supports_deleting_joins?() click to toggle source

Whether deleting from joined datasets is supported, false by default.

   # File lib/sequel/dataset/features.rb
55 def supports_deleting_joins?
56   supports_modifying_joins?
57 end
supports_derived_column_lists?() click to toggle source

Whether the database supports derived column lists (e.g. “table_expr AS table_alias(column_alias1, column_alias2, …)”), true by default.

   # File lib/sequel/dataset/features.rb
62 def supports_derived_column_lists?
63   true
64 end
supports_distinct_on?() click to toggle source

Whether the dataset supports or can emulate the DISTINCT ON clause, false by default.

   # File lib/sequel/dataset/features.rb
67 def supports_distinct_on?
68   false
69 end
supports_group_cube?() click to toggle source

Whether the dataset supports CUBE with GROUP BY, false by default.

   # File lib/sequel/dataset/features.rb
72 def supports_group_cube?
73   false
74 end
supports_group_rollup?() click to toggle source

Whether the dataset supports ROLLUP with GROUP BY, false by default.

   # File lib/sequel/dataset/features.rb
77 def supports_group_rollup?
78   false
79 end
supports_grouping_sets?() click to toggle source

Whether the dataset supports GROUPING SETS with GROUP BY, false by default.

   # File lib/sequel/dataset/features.rb
82 def supports_grouping_sets?
83   false
84 end
supports_insert_select?() click to toggle source

Whether this dataset supports the insert_select method for returning all columns values directly from an insert query, false by default.

   # File lib/sequel/dataset/features.rb
88 def supports_insert_select?
89   supports_returning?(:insert)
90 end
supports_intersect_except?() click to toggle source

Whether the dataset supports the INTERSECT and EXCEPT compound operations, true by default.

   # File lib/sequel/dataset/features.rb
93 def supports_intersect_except?
94   true
95 end
supports_intersect_except_all?() click to toggle source

Whether the dataset supports the INTERSECT ALL and EXCEPT ALL compound operations, true by default.

    # File lib/sequel/dataset/features.rb
 98 def supports_intersect_except_all?
 99   true
100 end
supports_is_true?() click to toggle source

Whether the dataset supports the IS TRUE syntax, true by default.

    # File lib/sequel/dataset/features.rb
103 def supports_is_true?
104   true
105 end
supports_join_using?() click to toggle source

Whether the dataset supports the JOIN table USING (column1, …) syntax, true by default. If false, support is emulated using JOIN table ON (table.column1 = other_table.column1).

    # File lib/sequel/dataset/features.rb
109 def supports_join_using?
110   true
111 end
supports_lateral_subqueries?() click to toggle source

Whether the dataset supports LATERAL for subqueries in the FROM or JOIN clauses, false by default.

    # File lib/sequel/dataset/features.rb
114 def supports_lateral_subqueries?
115   false
116 end
supports_limits_in_correlated_subqueries?() click to toggle source

Whether limits are supported in correlated subqueries, true by default.

    # File lib/sequel/dataset/features.rb
119 def supports_limits_in_correlated_subqueries?
120   true
121 end
supports_merge?() click to toggle source

Whether the MERGE statement is supported, false by default.

    # File lib/sequel/dataset/features.rb
129 def supports_merge?
130   false
131 end
supports_modifying_joins?() click to toggle source

Whether modifying joined datasets is supported, false by default.

    # File lib/sequel/dataset/features.rb
134 def supports_modifying_joins?
135   false
136 end
supports_multiple_column_in?() click to toggle source

Whether the IN/NOT IN operators support multiple columns when an array of values is given, true by default.

    # File lib/sequel/dataset/features.rb
140 def supports_multiple_column_in?
141   true
142 end
supports_nowait?() click to toggle source

Whether the dataset supports skipping raising an error instead of waiting for locked rows when returning data, false by default.

    # File lib/sequel/dataset/features.rb
124 def supports_nowait?
125   false
126 end
supports_offsets_in_correlated_subqueries?() click to toggle source

Whether offsets are supported in correlated subqueries, true by default.

    # File lib/sequel/dataset/features.rb
145 def supports_offsets_in_correlated_subqueries?
146   true
147 end
supports_ordered_distinct_on?() click to toggle source

Whether the dataset supports or can fully emulate the DISTINCT ON clause, including respecting the ORDER BY clause, false by default.

    # File lib/sequel/dataset/features.rb
151 def supports_ordered_distinct_on?
152   supports_distinct_on?
153 end
supports_regexp?() click to toggle source

Whether the dataset supports pattern matching by regular expressions, false by default.

    # File lib/sequel/dataset/features.rb
156 def supports_regexp?
157   false
158 end
supports_replace?() click to toggle source

Whether the dataset supports REPLACE syntax, false by default.

    # File lib/sequel/dataset/features.rb
161 def supports_replace?
162   false
163 end
supports_returning?(type) click to toggle source

Whether the RETURNING clause is supported for the given type of query, false by default. type can be :insert, :update, or :delete.

    # File lib/sequel/dataset/features.rb
167 def supports_returning?(type)
168   false
169 end
supports_select_all_and_column?() click to toggle source

Whether the database supports SELECT *, column FROM table, true by default.

    # File lib/sequel/dataset/features.rb
177 def supports_select_all_and_column?
178   true
179 end
supports_skip_locked?() click to toggle source

Whether the dataset supports skipping locked rows when returning data, false by default.

    # File lib/sequel/dataset/features.rb
172 def supports_skip_locked?
173   false
174 end
supports_timestamp_timezones?() click to toggle source

Whether the dataset supports timezones in literal timestamps, false by default.

    # File lib/sequel/dataset/features.rb
182 def supports_timestamp_timezones?
183   false
184 end
supports_timestamp_usecs?() click to toggle source

Whether the dataset supports fractional seconds in literal timestamps, true by default.

    # File lib/sequel/dataset/features.rb
187 def supports_timestamp_usecs?
188   true
189 end
supports_updating_joins?() click to toggle source

Whether updating joined datasets is supported, false by default.

    # File lib/sequel/dataset/features.rb
192 def supports_updating_joins?
193   supports_modifying_joins?
194 end
supports_where_true?() click to toggle source

Whether the dataset supports WHERE TRUE (or WHERE 1 for databases that that use 1 for true), true by default.

    # File lib/sequel/dataset/features.rb
221 def supports_where_true?
222   true
223 end
supports_window_clause?() click to toggle source

Whether the dataset supports the WINDOW clause to define windows used by multiple window functions, false by default.

    # File lib/sequel/dataset/features.rb
198 def supports_window_clause?
199   false
200 end
supports_window_function_frame_option?(option) click to toggle source

Whether the dataset supports the given window function option. True by default. This should only be called if supports_window_functions? is true. Possible options are :rows, :range, :groups, :offset, :exclude.

    # File lib/sequel/dataset/features.rb
210 def supports_window_function_frame_option?(option)
211   case option
212   when :rows, :range, :offset
213     true
214   else
215     false
216   end
217 end
supports_window_functions?() click to toggle source

Whether the dataset supports window functions, false by default.

    # File lib/sequel/dataset/features.rb
203 def supports_window_functions?
204   false
205 end

Private Instance Methods

insert_supports_empty_values?() click to toggle source

Whether insert(nil) or insert({}) must be emulated by using at least one value.

    # File lib/sequel/dataset/features.rb
229 def insert_supports_empty_values?
230   true
231 end
requires_emulating_nulls_first?() click to toggle source

Whether ORDER BY col NULLS FIRST/LAST must be emulated.

    # File lib/sequel/dataset/features.rb
239 def requires_emulating_nulls_first?
240   false
241 end
requires_like_escape?() click to toggle source

Whether the dataset needs ESCAPE for LIKE for correct behavior.

    # File lib/sequel/dataset/features.rb
234 def requires_like_escape?
235   true
236 end
supports_cte_in_compounds?() click to toggle source

Whether common table expressions are supported in UNION/INTERSECT/EXCEPT clauses.

    # File lib/sequel/dataset/features.rb
244 def supports_cte_in_compounds?
245   supports_cte_in_subqueries?
246 end
supports_filtered_aggregates?() click to toggle source

Whether the dataset supports the FILTER clause for aggregate functions. If not, support is emulated using CASE.

    # File lib/sequel/dataset/features.rb
250 def supports_filtered_aggregates?
251   false
252 end
supports_quoted_function_names?() click to toggle source

Whether the database supports quoting function names.

    # File lib/sequel/dataset/features.rb
255 def supports_quoted_function_names?
256   false
257 end
uses_returning?(type) click to toggle source

Whether the RETURNING clause is used for the given dataset. type can be :insert, :update, or :delete.

    # File lib/sequel/dataset/features.rb
261 def uses_returning?(type)
262   opts[:returning] && !@opts[:sql] && supports_returning?(type)
263 end
uses_with_rollup?() click to toggle source

Whether the dataset uses WITH ROLLUP/CUBE instead of ROLLUP()/CUBE().

    # File lib/sequel/dataset/features.rb
266 def uses_with_rollup?
267   false
268 end

5 - Methods related to dataset graphing

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Public Instance Methods

add_graph_aliases(graph_aliases) click to toggle source

Adds the given graph aliases to the list of graph aliases to use, unlike set_graph_aliases, which replaces the list (the equivalent of select_append when graphing). See set_graph_aliases.

DB[:table].add_graph_aliases(some_alias: [:table, :column])
# SELECT ..., table.column AS some_alias
   # File lib/sequel/dataset/graph.rb
18 def add_graph_aliases(graph_aliases)
19   graph = opts[:graph]
20   unless (graph && (ga = graph[:column_aliases]))
21     raise Error, "cannot call add_graph_aliases on a dataset that has not been called with graph or set_graph_aliases"
22   end
23   columns, graph_aliases = graph_alias_columns(graph_aliases)
24   select_append(*columns).clone(:graph => graph.merge(:column_aliases=>ga.merge(graph_aliases).freeze).freeze)
25 end
graph(dataset, join_conditions = nil, options = OPTS, &block) click to toggle source

Similar to Dataset#join_table, but uses unambiguous aliases for selected columns and keeps metadata about the aliases for use in other methods.

Arguments:

dataset

Can be a symbol (specifying a table), another dataset, or an SQL::Identifier, SQL::QualifiedIdentifier, or SQL::AliasedExpression.

join_conditions

Any condition(s) allowed by join_table.

block

A block that is passed to join_table.

Options:

:from_self_alias

The alias to use when the receiver is not a graphed dataset but it contains multiple FROM tables or a JOIN. In this case, the receiver is wrapped in a from_self before graphing, and this option determines the alias to use.

:implicit_qualifier

The qualifier of implicit conditions, see join_table.

:join_only

Only join the tables, do not change the selected columns.

:join_type

The type of join to use (passed to join_table). Defaults to :left_outer.

:qualify

The type of qualification to do, see join_table.

:select

An array of columns to select. When not used, selects all columns in the given dataset. When set to false, selects no columns and is like simply joining the tables, though graph keeps some metadata about the join that makes it important to use graph instead of join_table.

:table_alias

The alias to use for the table. If not specified, doesn't alias the table. You will get an error if the alias (or table) name is used more than once.

    # File lib/sequel/dataset/graph.rb
 53 def graph(dataset, join_conditions = nil, options = OPTS, &block)
 54   # Allow the use of a dataset or symbol as the first argument
 55   # Find the table name/dataset based on the argument
 56   table_alias = options[:table_alias]
 57   table = dataset
 58   create_dataset = true
 59 
 60   case dataset
 61   when Symbol
 62     # let alias be the same as the table name (sans any optional schema)
 63     # unless alias explicitly given in the symbol using ___ notation and symbol splitting is enabled
 64     table_alias ||= split_symbol(table).compact.last
 65   when Dataset
 66     if dataset.simple_select_all?
 67       table = dataset.opts[:from].first
 68       table_alias ||= table
 69     else
 70       table_alias ||= dataset_alias((@opts[:num_dataset_sources] || 0)+1)
 71     end
 72     create_dataset = false
 73   when SQL::Identifier
 74     table_alias ||= table.value
 75   when SQL::QualifiedIdentifier
 76     table_alias ||= split_qualifiers(table).last
 77   when SQL::AliasedExpression
 78     return graph(table.expression, join_conditions, {:table_alias=>table.alias}.merge!(options), &block)
 79   else
 80     raise Error, "The dataset argument should be a symbol or dataset"
 81   end
 82   table_alias = table_alias.to_sym
 83 
 84   if create_dataset
 85     dataset = db.from(table)
 86   end
 87 
 88   # Raise Sequel::Error with explanation that the table alias has been used
 89   raise_alias_error = lambda do
 90     raise(Error, "this #{options[:table_alias] ? 'alias' : 'table'} has already been been used, please specify " \
 91       "#{options[:table_alias] ? 'a different alias' : 'an alias via the :table_alias option'}") 
 92   end
 93 
 94   # Only allow table aliases that haven't been used
 95   raise_alias_error.call if @opts[:graph] && @opts[:graph][:table_aliases] && @opts[:graph][:table_aliases].include?(table_alias)
 96   
 97   table_alias_qualifier = qualifier_from_alias_symbol(table_alias, table)
 98   implicit_qualifier = options[:implicit_qualifier]
 99   joined_dataset = joined_dataset?
100   ds = self
101   graph = opts[:graph]
102 
103   if !graph && (select = @opts[:select]) && !select.empty?
104     select_columns = nil
105 
106     unless !joined_dataset && select.length == 1 && (select[0].is_a?(SQL::ColumnAll))
107       force_from_self = false
108       select_columns = select.map do |sel|
109         unless col = _hash_key_symbol(sel)
110           force_from_self = true
111           break
112         end
113 
114         [sel, col]
115       end
116 
117       select_columns = nil if force_from_self
118     end
119   end
120 
121   # Use a from_self if this is already a joined table (or from_self specifically disabled for graphs)
122   if (@opts[:graph_from_self] != false && !graph && (joined_dataset || force_from_self))
123     from_selfed = true
124     implicit_qualifier = options[:from_self_alias] || first_source
125     ds = ds.from_self(:alias=>implicit_qualifier)
126   end
127   
128   # Join the table early in order to avoid cloning the dataset twice
129   ds = ds.join_table(options[:join_type] || :left_outer, table, join_conditions, :table_alias=>table_alias_qualifier, :implicit_qualifier=>implicit_qualifier, :qualify=>options[:qualify], &block)
130 
131   return ds if options[:join_only]
132 
133   opts = ds.opts
134 
135   # Whether to include the table in the result set
136   add_table = options[:select] == false ? false : true
137 
138   if graph
139     graph = graph.dup
140     select = opts[:select].dup
141     [:column_aliases, :table_aliases, :column_alias_num].each{|k| graph[k] = graph[k].dup}
142   else
143     # Setup the initial graph data structure if it doesn't exist
144     qualifier = ds.first_source_alias
145     master = alias_symbol(qualifier)
146     raise_alias_error.call if master == table_alias
147 
148     # Master hash storing all .graph related information
149     graph = {}
150 
151     # Associates column aliases back to tables and columns
152     column_aliases = graph[:column_aliases] = {}
153 
154     # Associates table alias (the master is never aliased)
155     table_aliases = graph[:table_aliases] = {master=>self}
156 
157     # Keep track of the alias numbers used
158     ca_num = graph[:column_alias_num] = Hash.new(0)
159 
160     select = if select_columns
161       select_columns.map do |sel, column|
162         column_aliases[column] = [master, column]
163         if from_selfed
164           # Initial dataset was wrapped in subselect, selected all
165           # columns in the subselect, qualified by the subselect alias.
166           Sequel.qualify(qualifier, Sequel.identifier(column))
167         else
168           # Initial dataset not wrapped in subslect, just make
169           # sure columns are qualified in some way.
170           qualified_expression(sel, qualifier)
171         end
172       end
173     else
174       columns.map do |column|
175         column_aliases[column] = [master, column]
176         SQL::QualifiedIdentifier.new(qualifier, column)
177       end
178     end
179   end
180 
181   # Add the table alias to the list of aliases
182   # Even if it isn't been used in the result set,
183   # we add a key for it with a nil value so we can check if it
184   # is used more than once
185   table_aliases = graph[:table_aliases]
186   table_aliases[table_alias] = add_table ? dataset : nil
187 
188   # Add the columns to the selection unless we are ignoring them
189   if add_table
190     column_aliases = graph[:column_aliases]
191     ca_num = graph[:column_alias_num]
192     # Which columns to add to the result set
193     cols = options[:select] || dataset.columns
194     # If the column hasn't been used yet, don't alias it.
195     # If it has been used, try table_column.
196     # If that has been used, try table_column_N
197     # using the next value of N that we know hasn't been
198     # used
199     cols.each do |column|
200       col_alias, identifier = if column_aliases[column]
201         column_alias = :"#{table_alias}_#{column}"
202         if column_aliases[column_alias]
203           column_alias_num = ca_num[column_alias]
204           column_alias = :"#{column_alias}_#{column_alias_num}" 
205           ca_num[column_alias] += 1
206         end
207         [column_alias, SQL::AliasedExpression.new(SQL::QualifiedIdentifier.new(table_alias_qualifier, column), column_alias)]
208       else
209         ident = SQL::QualifiedIdentifier.new(table_alias_qualifier, column)
210         [column, ident]
211       end
212       column_aliases[col_alias] = [table_alias, column].freeze
213       select.push(identifier)
214     end
215   end
216   [:column_aliases, :table_aliases, :column_alias_num].each{|k| graph[k].freeze}
217   ds = ds.clone(:graph=>graph.freeze)
218   ds.select(*select)
219 end
set_graph_aliases(graph_aliases) click to toggle source

This allows you to manually specify the graph aliases to use when using graph. You can use it to only select certain columns, and have those columns mapped to specific aliases in the result set. This is the equivalent of select for a graphed dataset, and must be used instead of select whenever graphing is used.

graph_aliases should be a hash with keys being symbols of column aliases, and values being either symbols or arrays with one to three elements. If the value is a symbol, it is assumed to be the same as a one element array containing that symbol. The first element of the array should be the table alias symbol. The second should be the actual column name symbol. If the array only has a single element the column name symbol will be assumed to be the same as the corresponding hash key. If the array has a third element, it is used as the value returned, instead of table_alias.column_name.

DB[:artists].graph(:albums, :artist_id: :id).
  set_graph_aliases(name: :artists,
                    album_name: [:albums, :name],
                    forty_two: [:albums, :fourtwo, 42]).first
# SELECT artists.name, albums.name AS album_name, 42 AS forty_two ...
    # File lib/sequel/dataset/graph.rb
244 def set_graph_aliases(graph_aliases)
245   columns, graph_aliases = graph_alias_columns(graph_aliases)
246   if graph = opts[:graph]
247     select(*columns).clone(:graph => graph.merge(:column_aliases=>graph_aliases.freeze).freeze)
248   else
249     raise Error, "cannot call #set_graph_aliases on an ungraphed dataset"
250   end
251 end
ungraphed() click to toggle source

Remove the splitting of results into subhashes, and all metadata related to the current graph (if any).

    # File lib/sequel/dataset/graph.rb
255 def ungraphed
256   clone(:graph=>nil)
257 end

Private Instance Methods

graph_alias_columns(graph_aliases) click to toggle source

Transform the hash of graph aliases and return a two element array where the first element is an array of identifiers suitable to pass to a select method, and the second is a new hash of preprocessed graph aliases.

    # File lib/sequel/dataset/graph.rb
283 def graph_alias_columns(graph_aliases)
284   gas = {}
285   identifiers = graph_aliases.map do |col_alias, tc| 
286     table, column, value = Array(tc)
287     column ||= col_alias
288     gas[col_alias] = [table, column].freeze
289     identifier = value || SQL::QualifiedIdentifier.new(table, column)
290     identifier = SQL::AliasedExpression.new(identifier, col_alias) if value || column != col_alias
291     identifier
292   end
293   [identifiers, gas]
294 end
qualifier_from_alias_symbol(aliaz, identifier) click to toggle source

Wrap the alias symbol in an SQL::Identifier if the identifier on which is based is an SQL::Identifier. This works around cases where symbol splitting is enabled and the alias symbol contains double embedded underscores which would be considered an implicit qualified identifier if not wrapped in an SQL::Identifier.

    # File lib/sequel/dataset/graph.rb
265 def qualifier_from_alias_symbol(aliaz, identifier)
266   case identifier
267   when SQL::QualifiedIdentifier
268     if identifier.column.is_a?(String)
269       Sequel.identifier(aliaz)
270     else
271       aliaz
272     end
273   when SQL::Identifier
274     Sequel.identifier(aliaz)
275   else
276     aliaz
277   end
278 end

6 - Miscellaneous methods

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Attributes

cache[R]

Access the cache for the current dataset. Should be used with caution, as access to the cache is not thread safe without a mutex if other threads can reference the dataset. Symbol keys prefixed with an underscore are reserved for internal use.

db[R]

The database related to this dataset. This is the Database instance that will execute all of this dataset's queries.

opts[R]

The hash of options for this dataset, keys are symbols.

Public Class Methods

new(db) click to toggle source

Constructs a new Dataset instance with an associated database and options. Datasets are usually constructed by invoking the Database#[] method:

DB[:posts]

Sequel::Dataset is an abstract class that is not useful by itself. Each database adapter provides a subclass of Sequel::Dataset, and has the Database#dataset method return an instance of that subclass.

   # File lib/sequel/dataset/misc.rb
25 def initialize(db)
26   @db = db
27   @opts = OPTS
28   @cache = {}
29   freeze
30 end

Public Instance Methods

==(o) click to toggle source

Define a hash value such that datasets with the same class, DB, and opts will be considered equal.

   # File lib/sequel/dataset/misc.rb
34 def ==(o)
35   o.is_a?(self.class) && db == o.db && opts == o.opts
36 end
current_datetime() click to toggle source

An object representing the current date or time, should be an instance of Sequel.datetime_class.

   # File lib/sequel/dataset/misc.rb
40 def current_datetime
41   Sequel.datetime_class.now
42 end
dup() click to toggle source

Return self, as datasets are always frozen.

   # File lib/sequel/dataset/misc.rb
50 def dup
51   self
52 end
each_server() { |server(s)| ... } click to toggle source

Yield a dataset for each server in the connection pool that is tied to that server. Intended for use in sharded environments where all servers need to be modified with the same data:

DB[:configs].where(key: 'setting').each_server{|ds| ds.update(value: 'new_value')}
   # File lib/sequel/dataset/misc.rb
59 def each_server
60   db.servers.each{|s| yield server(s)}
61 end
eql?(o) click to toggle source

Alias for ==

   # File lib/sequel/dataset/misc.rb
45 def eql?(o)
46   self == o
47 end
escape_like(string) click to toggle source

Returns the string with the LIKE metacharacters (% and _) escaped. Useful for when the LIKE term is a user-provided string where metacharacters should not be recognized. Example:

ds.escape_like("foo\\%_") # 'foo\\\%\_'
   # File lib/sequel/dataset/misc.rb
68 def escape_like(string)
69   string.gsub(/[\\%_]/){|m| "\\#{m}"}
70 end
first_source() click to toggle source

Alias of first_source_alias

   # File lib/sequel/dataset/misc.rb
91 def first_source
92   first_source_alias
93 end
first_source_alias() click to toggle source

The first source (primary table) for this dataset. If the dataset doesn't have a table, raises an Error. If the table is aliased, returns the aliased name.

DB[:table].first_source_alias
# => :table

DB[Sequel[:table].as(:t)].first_source_alias
# => :t
    # File lib/sequel/dataset/misc.rb
103 def first_source_alias
104   source = @opts[:from]
105   if source.nil? || source.empty?
106     raise Error, 'No source specified for query'
107   end
108   case s = source.first
109   when SQL::AliasedExpression
110     s.alias
111   when Symbol
112     _, _, aliaz = split_symbol(s)
113     aliaz ? aliaz.to_sym : s
114   else
115     s
116   end
117 end
first_source_table() click to toggle source

The first source (primary table) for this dataset. If the dataset doesn't have a table, raises an error. If the table is aliased, returns the original table, not the alias

DB[:table].first_source_table
# => :table

DB[Sequel[:table].as(:t)].first_source_table
# => :table
    # File lib/sequel/dataset/misc.rb
128 def first_source_table
129   source = @opts[:from]
130   if source.nil? || source.empty?
131     raise Error, 'No source specified for query'
132   end
133   case s = source.first
134   when SQL::AliasedExpression
135     s.expression
136   when Symbol
137     sch, table, aliaz = split_symbol(s)
138     aliaz ? (sch ? SQL::QualifiedIdentifier.new(sch, table) : table.to_sym) : s
139   else
140     s
141   end
142 end
freeze() click to toggle source

Freeze the opts when freezing the dataset.

Calls superclass method
   # File lib/sequel/dataset/misc.rb
74 def freeze
75   @opts.freeze
76   super
77 end
hash() click to toggle source

Define a hash value such that datasets with the same class, DB, and opts, will have the same hash value.

    # File lib/sequel/dataset/misc.rb
146 def hash
147   [self.class, db, opts].hash
148 end
inspect() click to toggle source

Returns a string representation of the dataset including the class name and the corresponding SQL select statement.

    # File lib/sequel/dataset/misc.rb
152 def inspect
153   "#<#{visible_class_name}: #{sql.inspect}>"
154 end
joined_dataset?() click to toggle source

Whether this dataset is a joined dataset (multiple FROM tables or any JOINs).

    # File lib/sequel/dataset/misc.rb
157 def joined_dataset?
158  !!((opts[:from].is_a?(Array) && opts[:from].size > 1) || opts[:join])
159 end
row_number_column() click to toggle source

The alias to use for the row_number column, used when emulating OFFSET support and for eager limit strategies

    # File lib/sequel/dataset/misc.rb
163 def row_number_column
164   :x_sequel_row_number_x
165 end
row_proc() click to toggle source

The row_proc for this database, should be any object that responds to call with a single hash argument and returns the object you want each to return.

    # File lib/sequel/dataset/misc.rb
169 def row_proc
170   @opts[:row_proc]
171 end
split_alias(c) click to toggle source

Splits a possible implicit alias in c, handling both SQL::AliasedExpressions and Symbols. Returns an array of two elements, with the first being the main expression, and the second being the alias.

    # File lib/sequel/dataset/misc.rb
176 def split_alias(c)
177   case c
178   when Symbol
179     c_table, column, aliaz = split_symbol(c)
180     [c_table ? SQL::QualifiedIdentifier.new(c_table, column.to_sym) : column.to_sym, aliaz]
181   when SQL::AliasedExpression
182     [c.expression, c.alias]
183   when SQL::JoinClause
184     [c.table, c.table_alias]
185   else
186     [c, nil]
187   end
188 end
unqualified_column_for(v) click to toggle source

This returns an SQL::Identifier or SQL::AliasedExpression containing an SQL identifier that represents the unqualified column for the given value. The given value should be a Symbol, SQL::Identifier, SQL::QualifiedIdentifier, or SQL::AliasedExpression containing one of those. In other cases, this returns nil.

    # File lib/sequel/dataset/misc.rb
195 def unqualified_column_for(v)
196   unless v.is_a?(String)
197     _unqualified_column_for(v)
198   end
199 end
unused_table_alias(table_alias, used_aliases = []) click to toggle source

Creates a unique table alias that hasn't already been used in the dataset. table_alias can be any type of object accepted by alias_symbol. The symbol returned will be the implicit alias in the argument, possibly appended with “_N” if the implicit alias has already been used, where N is an integer starting at 0 and increasing until an unused one is found.

You can provide a second addition array argument containing symbols that should not be considered valid table aliases. The current aliases for the FROM and JOIN tables are automatically included in this array.

DB[:table].unused_table_alias(:t)
# => :t

DB[:table].unused_table_alias(:table)
# => :table_0

DB[:table, :table_0].unused_table_alias(:table)
# => :table_1

DB[:table, :table_0].unused_table_alias(:table, [:table_1, :table_2])
# => :table_3
    # File lib/sequel/dataset/misc.rb
223 def unused_table_alias(table_alias, used_aliases = [])
224   table_alias = alias_symbol(table_alias)
225   used_aliases += opts[:from].map{|t| alias_symbol(t)} if opts[:from]
226   used_aliases += opts[:join].map{|j| j.table_alias ? alias_alias_symbol(j.table_alias) : alias_symbol(j.table)} if opts[:join]
227   if used_aliases.include?(table_alias)
228     i = 0
229     while true
230       ta = :"#{table_alias}_#{i}"
231       return ta unless used_aliases.include?(ta)
232       i += 1 
233     end
234   else
235     table_alias
236   end
237 end
with_quote_identifiers(v) click to toggle source

Return a modified dataset with quote_identifiers set.

    # File lib/sequel/dataset/misc.rb
240 def with_quote_identifiers(v)
241   clone(:quote_identifiers=>v, :skip_symbol_cache=>true)
242 end

Protected Instance Methods

_columns() click to toggle source

The cached columns for the current dataset.

    # File lib/sequel/dataset/misc.rb
271 def _columns
272   cache_get(:_columns)
273 end
cache_get(k) click to toggle source

Retreive a value from the dataset's cache in a thread safe manner.

    # File lib/sequel/dataset/misc.rb
253 def cache_get(k)
254   Sequel.synchronize{@cache[k]}
255 end
cache_set(k, v) click to toggle source

Set a value in the dataset's cache in a thread safe manner.

    # File lib/sequel/dataset/misc.rb
258 def cache_set(k, v)
259   Sequel.synchronize{@cache[k] = v}
260 end
clear_columns_cache() click to toggle source

Clear the columns hash for the current dataset. This is not a thread safe operation, so it should only be used if the dataset could not be used by another thread (such as one that was just created via clone).

    # File lib/sequel/dataset/misc.rb
266 def clear_columns_cache
267   @cache.delete(:_columns)
268 end

Private Instance Methods

_unqualified_column_for(v) click to toggle source

Internal recursive version of unqualified_column_for, handling Strings inside of other objects.

    # File lib/sequel/dataset/misc.rb
345 def _unqualified_column_for(v)
346   case v
347   when Symbol
348     _, c, a = Sequel.split_symbol(v)
349     c = Sequel.identifier(c)
350     a ? c.as(a) : c
351   when String
352     Sequel.identifier(v)
353   when SQL::Identifier
354     v
355   when SQL::QualifiedIdentifier
356     _unqualified_column_for(v.column)
357   when SQL::AliasedExpression
358     if expr = unqualified_column_for(v.expression)
359       SQL::AliasedExpression.new(expr, v.alias)
360     end
361   end
362 end
cached_dataset(key) { || ... } click to toggle source

Check the cache for the given key, returning the value. Otherwise, yield to get the dataset and cache the dataset under the given key.

    # File lib/sequel/dataset/misc.rb
279 def cached_dataset(key)
280   unless ds = cache_get(key)
281     ds = yield
282     cache_set(key, ds)
283   end
284 
285   ds
286 end
cached_placeholder_literalizer(key) { |pl| ... } click to toggle source

Return a cached placeholder literalizer for the given key if there is one for this dataset. If there isn't one, increment the counter for the number of calls for the key, and if the counter is at least three, then create a placeholder literalizer by yielding to the block, and cache it.

    # File lib/sequel/dataset/misc.rb
293 def cached_placeholder_literalizer(key)
294   if loader = cache_get(key)
295     return loader unless loader.is_a?(Integer)
296     loader += 1
297 
298     if loader >= 3
299       loader = Sequel::Dataset::PlaceholderLiteralizer.loader(self){|pl, _| yield pl}
300       cache_set(key, loader)
301     else
302       cache_set(key, loader + 1)
303       loader = nil
304     end
305   elsif cache_sql?
306     cache_set(key, 1)
307   end
308 
309   loader
310 end
cached_where_placeholder_literalizer(where_args, where_block, key, &block) click to toggle source

Return a cached placeholder literalizer for the key, unless where_block is nil and where_args is an empty array or hash. This is designed to guard against placeholder literalizer use when passing arguments to where in the uncached case and filter_expr if a cached placeholder literalizer is used.

    # File lib/sequel/dataset/misc.rb
317 def cached_where_placeholder_literalizer(where_args, where_block, key, &block)
318   where_args = where_args[0] if where_args.length == 1
319   unless where_block
320     return if where_args == OPTS || where_args == EMPTY_ARRAY
321   end
322 
323   cached_placeholder_literalizer(key, &block)
324 end
columns=(v) click to toggle source

Set the columns for the current dataset.

    # File lib/sequel/dataset/misc.rb
327 def columns=(v)
328   cache_set(:_columns, v)
329 end
initialize_clone(c, _=nil) click to toggle source

Set the db, opts, and cache for the copy of the dataset.

    # File lib/sequel/dataset/misc.rb
332 def initialize_clone(c, _=nil)
333   @db = c.db
334   @opts = Hash[c.opts]
335   if cols = c.cache_get(:_columns)
336     @cache = {:_columns=>cols}
337   else
338     @cache = {}
339   end
340 end
Also aliased as: initialize_copy
initialize_copy(c, _=nil)
Alias for: initialize_clone
visible_class_name() click to toggle source

Return the class name for this dataset, but skip anonymous classes

    # File lib/sequel/dataset/misc.rb
365 def visible_class_name
366   c = self.class
367   c = c.superclass while c.name.nil? || c.name == ''
368   c.name
369 end

8 - Methods related to prepared statements or bound variables

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Constants

DEFAULT_PREPARED_STATEMENT_MODULE_METHODS
PREPARED_ARG_PLACEHOLDER
PREPARED_STATEMENT_MODULE_CODE

Private Class Methods

prepared_statements_module(code, mods, meths=DEFAULT_PREPARED_STATEMENT_MODULE_METHODS, &block) click to toggle source
   # File lib/sequel/dataset/prepared_statements.rb
20 def self.prepared_statements_module(code, mods, meths=DEFAULT_PREPARED_STATEMENT_MODULE_METHODS, &block)
21   code = PREPARED_STATEMENT_MODULE_CODE[code] || code
22 
23   Module.new do
24     Array(mods).each do |mod|
25       include mod
26     end
27 
28     if block
29       module_eval(&block)
30     end
31 
32     meths.each do |meth|
33       module_eval("def #{meth}(sql, opts=Sequel::OPTS) #{code}; super end", __FILE__, __LINE__)
34     end
35     private(*meths)
36   end
37 end

Public Instance Methods

bind(bind_vars=OPTS) click to toggle source

Set the bind variables to use for the call. If bind variables have already been set for this dataset, they are updated with the contents of bind_vars.

DB[:table].where(id: :$id).bind(id: 1).call(:first)
# SELECT * FROM table WHERE id = ? LIMIT 1 -- (1)
# => {:id=>1}
    # File lib/sequel/dataset/prepared_statements.rb
332 def bind(bind_vars=OPTS)
333   bind_vars = if bv = @opts[:bind_vars]
334     bv.merge(bind_vars).freeze
335   else
336     if bind_vars.frozen?
337       bind_vars
338     else
339       Hash[bind_vars]
340     end
341   end
342 
343   clone(:bind_vars=>bind_vars)
344 end
call(type, bind_variables=OPTS, *values, &block) click to toggle source

For the given type (:select, :first, :insert, :insert_select, :update, :delete, or :single_value), run the sql with the bind variables specified in the hash. values is a hash passed to insert or update (if one of those types is used), which may contain placeholders.

DB[:table].where(id: :$id).call(:first, id: 1)
# SELECT * FROM table WHERE id = ? LIMIT 1 -- (1)
# => {:id=>1}
    # File lib/sequel/dataset/prepared_statements.rb
353 def call(type, bind_variables=OPTS, *values, &block)
354   to_prepared_statement(type, values, :extend=>bound_variable_modules).call(bind_variables, &block)
355 end
prepare(type, name, *values) click to toggle source

Prepare an SQL statement for later execution. Takes a type similar to call, and the name symbol of the prepared statement.

This returns a clone of the dataset extended with PreparedStatementMethods, which you can call with the hash of bind variables to use. The prepared statement is also stored in the associated Database, where it can be called by name. The following usage is identical:

ps = DB[:table].where(name: :$name).prepare(:first, :select_by_name)

ps.call(name: 'Blah')
# SELECT * FROM table WHERE name = ? -- ('Blah')
# => {:id=>1, :name=>'Blah'}

DB.call(:select_by_name, name: 'Blah') # Same thing
    # File lib/sequel/dataset/prepared_statements.rb
373 def prepare(type, name, *values)
374   ps = to_prepared_statement(type, values, :name=>name, :extend=>prepared_statement_modules, :no_delayed_evaluations=>true)
375 
376   ps = if ps.send(:emulate_prepared_statements?)
377     ps = ps.with_extend(EmulatePreparedStatementMethods)
378     ps.send(:emulated_prepared_statement, type, name, values)
379   else
380     sql = ps.prepared_sql
381     ps.prepared_args.freeze
382     ps.clone(:prepared_sql=>sql, :sql=>sql)
383   end
384 
385   db.set_prepared_statement(name, ps)
386   ps
387 end

Protected Instance Methods

to_prepared_statement(type, values=nil, opts=OPTS) click to toggle source

Return a cloned copy of the current dataset extended with PreparedStatementMethods, setting the type and modify values.

    # File lib/sequel/dataset/prepared_statements.rb
393 def to_prepared_statement(type, values=nil, opts=OPTS)
394   mods = opts[:extend] || []
395   mods += [PreparedStatementMethods]
396 
397   bind.
398     clone(:prepared_statement_name=>opts[:name], :prepared_type=>type, :prepared_modify_values=>values, :orig_dataset=>self, :no_cache_sql=>true, :prepared_args=>@opts[:prepared_args]||[], :no_delayed_evaluations=>opts[:no_delayed_evaluations]).
399     with_extend(*mods)
400 end

Private Instance Methods

allow_preparing_prepared_statements?() click to toggle source

Don't allow preparing prepared statements by default.

    # File lib/sequel/dataset/prepared_statements.rb
405 def allow_preparing_prepared_statements?
406   false
407 end
bound_variable_modules() click to toggle source
    # File lib/sequel/dataset/prepared_statements.rb
409 def bound_variable_modules
410   prepared_statement_modules
411 end
emulate_prepared_statements?() click to toggle source

Whether prepared statements should be emulated. True by default so that adapters have to opt in.

    # File lib/sequel/dataset/prepared_statements.rb
415 def emulate_prepared_statements?
416   true
417 end
prepared_arg_placeholder() click to toggle source

The argument placeholder. Most databases used unnumbered arguments with question marks, so that is the default.

    # File lib/sequel/dataset/prepared_statements.rb
425 def prepared_arg_placeholder
426   PREPARED_ARG_PLACEHOLDER
427 end
prepared_statement_modules() click to toggle source
    # File lib/sequel/dataset/prepared_statements.rb
419 def prepared_statement_modules
420   []
421 end

9 - Internal Methods relating to SQL Creation

↑ top

Constants

BITWISE_METHOD_MAP
COUNT_FROM_SELF_OPTS
COUNT_OF_ALL_AS_COUNT
DEFAULT
EXISTS
IS_LITERALS
IS_OPERATORS
LIKE_OPERATORS
MERGE_TYPE_SQL

Mapping of merge types to related SQL

N_ARITY_OPERATORS
QUALIFY_KEYS
REGEXP_OPERATORS
TWO_ARITY_OPERATORS
WILDCARD

Public Class Methods

clause_methods(type, clauses) click to toggle source

Given a type (e.g. select) and an array of clauses, return an array of methods to call to build the SQL string.

    # File lib/sequel/dataset/sql.rb
198 def self.clause_methods(type, clauses)
199   clauses.map{|clause| :"#{type}_#{clause}_sql"}.freeze
200 end
def_sql_method(mod, type, clauses) click to toggle source

Define a dataset literalization method for the given type in the given module, using the given clauses.

Arguments:

mod

Module in which to define method

type

Type of SQL literalization method to create, either :select, :insert, :update, or :delete

clauses

array of clauses that make up the SQL query for the type. This can either be a single array of symbols/strings, or it can be an array of pairs, with the first element in each pair being an if/elsif/else code fragment, and the second element in each pair being an array of symbol/strings for the appropriate branch.

    # File lib/sequel/dataset/sql.rb
212 def self.def_sql_method(mod, type, clauses)
213   priv = type == :update || type == :insert
214   cacheable = type == :select || type == :delete
215 
216   lines = []
217   lines << 'private' if priv
218   lines << "def #{'_' if priv}#{type}_sql"
219   lines << 'if sql = opts[:sql]; return static_sql(sql) end' unless priv
220   lines << "if sql = cache_get(:_#{type}_sql); return sql end" if cacheable
221   lines << 'check_delete_allowed!' << 'check_not_limited!(:delete)' if type == :delete
222   lines << 'sql = @opts[:append_sql] || sql_string_origin'
223 
224   if clauses.all?{|c| c.is_a?(Array)}
225     clauses.each do |i, cs|
226       lines << i
227       lines.concat(clause_methods(type, cs).map{|x| "#{x}(sql)"}) 
228     end 
229     lines << 'end'
230   else
231     lines.concat(clause_methods(type, clauses).map{|x| "#{x}(sql)"})
232   end
233 
234   lines << "cache_set(:_#{type}_sql, sql) if cache_sql?" if cacheable
235   lines << 'sql'
236   lines << 'end'
237 
238   mod.class_eval lines.join("\n"), __FILE__, __LINE__
239 end

Public Instance Methods

aliased_expression_sql_append(sql, ae) click to toggle source

Append literalization of aliased expression to SQL string.

    # File lib/sequel/dataset/sql.rb
273 def aliased_expression_sql_append(sql, ae)
274   literal_append(sql, ae.expression)
275   as_sql_append(sql, ae.alias, ae.columns)
276 end
array_sql_append(sql, a) click to toggle source

Append literalization of array to SQL string.

    # File lib/sequel/dataset/sql.rb
279 def array_sql_append(sql, a)
280   if a.empty?
281     sql << '(NULL)'
282   else
283     sql << '('
284     expression_list_append(sql, a)
285     sql << ')'
286   end
287 end
boolean_constant_sql_append(sql, constant) click to toggle source

Append literalization of boolean constant to SQL string.

    # File lib/sequel/dataset/sql.rb
290 def boolean_constant_sql_append(sql, constant)
291   if (constant == true || constant == false) && !supports_where_true?
292     sql << (constant == true ? '(1 = 1)' : '(1 = 0)')
293   else
294     literal_append(sql, constant)
295   end
296 end
case_expression_sql_append(sql, ce) click to toggle source

Append literalization of case expression to SQL string.

    # File lib/sequel/dataset/sql.rb
299 def case_expression_sql_append(sql, ce)
300   sql << '(CASE'
301   if ce.expression?
302     sql << ' '
303     literal_append(sql, ce.expression)
304   end
305   w = " WHEN "
306   t = " THEN "
307   ce.conditions.each do |c,r|
308     sql << w
309     literal_append(sql, c)
310     sql << t
311     literal_append(sql, r)
312   end
313   sql << " ELSE "
314   literal_append(sql, ce.default)
315   sql << " END)"
316 end
cast_sql_append(sql, expr, type) click to toggle source

Append literalization of cast expression to SQL string.

    # File lib/sequel/dataset/sql.rb
319 def cast_sql_append(sql, expr, type)
320   sql << 'CAST('
321   literal_append(sql, expr)
322   sql << ' AS ' << db.cast_type_literal(type).to_s
323   sql << ')'
324 end
column_all_sql_append(sql, ca) click to toggle source

Append literalization of column all selection to SQL string.

    # File lib/sequel/dataset/sql.rb
327 def column_all_sql_append(sql, ca)
328   qualified_identifier_sql_append(sql, ca.table, WILDCARD)
329 end
complex_expression_sql_append(sql, op, args) click to toggle source

Append literalization of complex expression to SQL string.

    # File lib/sequel/dataset/sql.rb
332 def complex_expression_sql_append(sql, op, args)
333   case op
334   when *IS_OPERATORS
335     r = args[1]
336     if r.nil? || supports_is_true?
337       raise(InvalidOperation, 'Invalid argument used for IS operator') unless val = IS_LITERALS[r]
338       sql << '('
339       literal_append(sql, args[0])
340       sql << ' ' << op.to_s << ' '
341       sql << val << ')'
342     elsif op == :IS
343       complex_expression_sql_append(sql, :"=", args)
344     else
345       complex_expression_sql_append(sql, :OR, [SQL::BooleanExpression.new(:"!=", *args), SQL::BooleanExpression.new(:IS, args[0], nil)])
346     end
347   when :IN, :"NOT IN"
348     cols = args[0]
349     vals = args[1]
350     col_array = true if cols.is_a?(Array)
351     if vals.is_a?(Array)
352       val_array = true
353       empty_val_array = vals == []
354     end
355     if empty_val_array
356       literal_append(sql, empty_array_value(op, cols))
357     elsif col_array
358       if !supports_multiple_column_in?
359         if val_array
360           expr = SQL::BooleanExpression.new(:OR, *vals.to_a.map{|vs| SQL::BooleanExpression.from_value_pairs(cols.to_a.zip(vs).map{|c, v| [c, v]})})
361           literal_append(sql, op == :IN ? expr : ~expr)
362         else
363           old_vals = vals
364           vals = vals.naked if vals.is_a?(Sequel::Dataset)
365           vals = vals.to_a
366           val_cols = old_vals.columns
367           complex_expression_sql_append(sql, op, [cols, vals.map!{|x| x.values_at(*val_cols)}])
368         end
369       else
370         # If the columns and values are both arrays, use array_sql instead of
371         # literal so that if values is an array of two element arrays, it
372         # will be treated as a value list instead of a condition specifier.
373         sql << '('
374         literal_append(sql, cols)
375         sql << ' ' << op.to_s << ' '
376         if val_array
377           array_sql_append(sql, vals)
378         else
379           literal_append(sql, vals)
380         end
381         sql << ')'
382       end
383     else
384       sql << '('
385       literal_append(sql, cols)
386       sql << ' ' << op.to_s << ' '
387       literal_append(sql, vals)
388       sql << ')'
389     end
390   when :LIKE, :'NOT LIKE'
391     sql << '('
392     literal_append(sql, args[0])
393     sql << ' ' << op.to_s << ' '
394     literal_append(sql, args[1])
395     if requires_like_escape?
396       sql << " ESCAPE "
397       literal_append(sql, "\\")
398     end
399     sql << ')'
400   when :ILIKE, :'NOT ILIKE'
401     complex_expression_sql_append(sql, (op == :ILIKE ? :LIKE : :"NOT LIKE"), args.map{|v| Sequel.function(:UPPER, v)})
402   when :**
403     function_sql_append(sql, Sequel.function(:power, *args))
404   when *TWO_ARITY_OPERATORS
405     if REGEXP_OPERATORS.include?(op) && !supports_regexp?
406       raise InvalidOperation, "Pattern matching via regular expressions is not supported on #{db.database_type}"
407     end
408     sql << '('
409     literal_append(sql, args[0])
410     sql << ' ' << op.to_s << ' '
411     literal_append(sql, args[1])
412     sql << ')'
413   when *N_ARITY_OPERATORS
414     sql << '('
415     c = false
416     op_str = " #{op} "
417     args.each do |a|
418       sql << op_str if c
419       literal_append(sql, a)
420       c ||= true
421     end
422     sql << ')'
423   when :NOT
424     sql << 'NOT '
425     literal_append(sql, args[0])
426   when :NOOP
427     literal_append(sql, args[0])
428   when :'B~'
429     sql << '~'
430     literal_append(sql, args[0])
431   when :extract
432     sql << 'extract(' << args[0].to_s << ' FROM '
433     literal_append(sql, args[1])
434     sql << ')'
435   else
436     raise(InvalidOperation, "invalid operator #{op}")
437   end
438 end
constant_sql_append(sql, constant) click to toggle source

Append literalization of constant to SQL string.

    # File lib/sequel/dataset/sql.rb
441 def constant_sql_append(sql, constant)
442   sql << constant.to_s
443 end
delayed_evaluation_sql_append(sql, delay) click to toggle source

Append literalization of delayed evaluation to SQL string, causing the delayed evaluation proc to be evaluated.

    # File lib/sequel/dataset/sql.rb
447 def delayed_evaluation_sql_append(sql, delay)
448   # Delayed evaluations are used specifically so the SQL
449   # can differ in subsequent calls, so we definitely don't
450   # want to cache the sql in this case.
451   disable_sql_caching!
452 
453   if recorder = @opts[:placeholder_literalizer]
454     recorder.use(sql, lambda{delay.call(self)}, nil)
455   else
456     literal_append(sql, delay.call(self))
457   end
458 end
function_sql_append(sql, f) click to toggle source

Append literalization of function call to SQL string.

    # File lib/sequel/dataset/sql.rb
461 def function_sql_append(sql, f)
462   name = f.name
463   opts = f.opts
464 
465   if opts[:emulate]
466     if emulate_function?(name)
467       emulate_function_sql_append(sql, f)
468       return
469     end
470 
471     name = native_function_name(name) 
472   end
473 
474   sql << 'LATERAL ' if opts[:lateral]
475 
476   case name
477   when SQL::Identifier
478     if supports_quoted_function_names? && opts[:quoted]
479       literal_append(sql, name)
480     else
481       sql << name.value.to_s
482     end
483   when SQL::QualifiedIdentifier
484     if supports_quoted_function_names? && opts[:quoted] != false
485       literal_append(sql, name)
486     else
487       sql << split_qualifiers(name).join('.')
488     end
489   else
490     if supports_quoted_function_names? && opts[:quoted]
491       quote_identifier_append(sql, name)
492     else
493       sql << name.to_s
494     end
495   end
496 
497   sql << '('
498   if filter = opts[:filter]
499     filter = filter_expr(filter, &opts[:filter_block])
500   end
501   if opts[:*]
502     if filter && !supports_filtered_aggregates?
503       literal_append(sql, Sequel.case({filter=>1}, nil))
504       filter = nil
505     else
506       sql <<  '*'
507     end
508   else
509     sql << "DISTINCT " if opts[:distinct]
510     if filter && !supports_filtered_aggregates?
511       expression_list_append(sql, f.args.map{|arg| Sequel.case({filter=>arg}, nil)})
512       filter = nil
513     else
514       expression_list_append(sql, f.args)
515     end
516     if order = opts[:order]
517       sql << " ORDER BY "
518       expression_list_append(sql, order)
519     end
520   end
521   sql << ')'
522 
523   if group = opts[:within_group]
524     sql << " WITHIN GROUP (ORDER BY "
525     expression_list_append(sql, group)
526     sql << ')'
527   end
528 
529   if filter
530     sql << " FILTER (WHERE "
531     literal_append(sql, filter)
532     sql << ')'
533   end
534 
535   if window = opts[:over]
536     sql << ' OVER '
537     window_sql_append(sql, window.opts)
538   end
539 
540   if opts[:with_ordinality]
541     sql << " WITH ORDINALITY"
542   end
543 end
join_clause_sql_append(sql, jc) click to toggle source

Append literalization of JOIN clause without ON or USING to SQL string.

    # File lib/sequel/dataset/sql.rb
546 def join_clause_sql_append(sql, jc)
547   table = jc.table
548   table_alias = jc.table_alias
549   table_alias = nil if table == table_alias && !jc.column_aliases
550   sql << ' ' << join_type_sql(jc.join_type) << ' '
551   identifier_append(sql, table)
552   as_sql_append(sql, table_alias, jc.column_aliases) if table_alias
553 end
join_on_clause_sql_append(sql, jc) click to toggle source

Append literalization of JOIN ON clause to SQL string.

    # File lib/sequel/dataset/sql.rb
556 def join_on_clause_sql_append(sql, jc)
557   join_clause_sql_append(sql, jc)
558   sql << ' ON '
559   literal_append(sql, filter_expr(jc.on))
560 end
join_using_clause_sql_append(sql, jc) click to toggle source

Append literalization of JOIN USING clause to SQL string.

    # File lib/sequel/dataset/sql.rb
563 def join_using_clause_sql_append(sql, jc)
564   join_clause_sql_append(sql, jc)
565   join_using_clause_using_sql_append(sql, jc.using) 
566 end
negative_boolean_constant_sql_append(sql, constant) click to toggle source

Append literalization of negative boolean constant to SQL string.

    # File lib/sequel/dataset/sql.rb
569 def negative_boolean_constant_sql_append(sql, constant)
570   sql << 'NOT '
571   boolean_constant_sql_append(sql, constant)
572 end
ordered_expression_sql_append(sql, oe) click to toggle source

Append literalization of ordered expression to SQL string.

    # File lib/sequel/dataset/sql.rb
575 def ordered_expression_sql_append(sql, oe)
576   if emulate = requires_emulating_nulls_first?
577     case oe.nulls
578     when :first
579       null_order = 0
580     when :last
581       null_order = 2
582     end
583 
584     if null_order
585       literal_append(sql, Sequel.case({{oe.expression=>nil}=>null_order}, 1))
586       sql << ", "
587     end
588   end
589 
590   literal_append(sql, oe.expression)
591   sql << (oe.descending ? ' DESC' : ' ASC')
592 
593   unless emulate
594     case oe.nulls
595     when :first
596       sql << " NULLS FIRST"
597     when :last
598       sql << " NULLS LAST"
599     end
600   end
601 end
placeholder_literal_string_sql_append(sql, pls) click to toggle source

Append literalization of placeholder literal string to SQL string.

    # File lib/sequel/dataset/sql.rb
604 def placeholder_literal_string_sql_append(sql, pls)
605   args = pls.args
606   str = pls.str
607   sql << '(' if pls.parens
608   if args.is_a?(Hash)
609     if args.empty?
610       sql << str
611     else
612       re = /:(#{args.keys.map{|k| Regexp.escape(k.to_s)}.join('|')})\b/
613       while true
614         previous, q, str = str.partition(re)
615         sql << previous
616         literal_append(sql, args[($1||q[1..-1].to_s).to_sym]) unless q.empty?
617         break if str.empty?
618       end
619     end
620   elsif str.is_a?(Array)
621     len = args.length
622     str.each_with_index do |s, i|
623       sql << s
624       literal_append(sql, args[i]) unless i == len
625     end
626     unless str.length == args.length || str.length == args.length + 1
627       raise Error, "Mismatched number of placeholders (#{str.length}) and placeholder arguments (#{args.length}) when using placeholder array"
628     end
629   else
630     i = -1
631     match_len = args.length - 1
632     while true
633       previous, q, str = str.partition('?')
634       sql << previous
635       literal_append(sql, args.at(i+=1)) unless q.empty?
636       if str.empty?
637         unless i == match_len
638           raise Error, "Mismatched number of placeholders (#{i+1}) and placeholder arguments (#{args.length}) when using placeholder string"
639         end
640         break
641       end
642     end
643   end
644   sql << ')' if pls.parens
645 end
qualified_identifier_sql_append(sql, table, column=(c = table.column; table = table.table; c)) click to toggle source

Append literalization of qualified identifier to SQL string. If 3 arguments are given, the 2nd should be the table/qualifier and the third should be column/qualified. If 2 arguments are given, the 2nd should be an SQL::QualifiedIdentifier.

    # File lib/sequel/dataset/sql.rb
650 def qualified_identifier_sql_append(sql, table, column=(c = table.column; table = table.table; c))
651   identifier_append(sql, table)
652   sql << '.'
653   identifier_append(sql, column)
654 end
quote_identifier_append(sql, name) click to toggle source

Append literalization of unqualified identifier to SQL string. Adds quoting to identifiers (columns and tables). If identifiers are not being quoted, returns name as a string. If identifiers are being quoted quote the name with quoted_identifier.

    # File lib/sequel/dataset/sql.rb
660 def quote_identifier_append(sql, name)
661   if name.is_a?(LiteralString)
662     sql << name
663   else
664     name = name.value if name.is_a?(SQL::Identifier)
665     name = input_identifier(name)
666     if quote_identifiers?
667       quoted_identifier_append(sql, name)
668     else
669       sql << name
670     end
671   end
672 end
quote_schema_table_append(sql, table) click to toggle source

Append literalization of identifier or unqualified identifier to SQL string.

    # File lib/sequel/dataset/sql.rb
675 def quote_schema_table_append(sql, table)
676   schema, table = schema_and_table(table)
677   if schema
678     quote_identifier_append(sql, schema)
679     sql << '.'
680   end
681   quote_identifier_append(sql, table)
682 end
quoted_identifier_append(sql, name) click to toggle source

Append literalization of quoted identifier to SQL string. This method quotes the given name with the SQL standard double quote. should be overridden by subclasses to provide quoting not matching the SQL standard, such as backtick (used by MySQL and SQLite).

    # File lib/sequel/dataset/sql.rb
688 def quoted_identifier_append(sql, name)
689   sql << '"' << name.to_s.gsub('"', '""') << '"'
690 end
schema_and_table(table_name, sch=nil) click to toggle source

Split the schema information from the table, returning two strings, one for the schema and one for the table. The returned schema may be nil, but the table will always have a string value.

Note that this function does not handle tables with more than one level of qualification (e.g. database.schema.table on Microsoft SQL Server).

    # File lib/sequel/dataset/sql.rb
699 def schema_and_table(table_name, sch=nil)
700   sch = sch.to_s if sch
701   case table_name
702   when Symbol
703     s, t, _ = split_symbol(table_name)
704     [s||sch, t]
705   when SQL::QualifiedIdentifier
706     [table_name.table.to_s, table_name.column.to_s]
707   when SQL::Identifier
708     [sch, table_name.value.to_s]
709   when String
710     [sch, table_name]
711   else
712     raise Error, 'table_name should be a Symbol, SQL::QualifiedIdentifier, SQL::Identifier, or String'
713   end
714 end
split_qualifiers(table_name, *args) click to toggle source

Splits table_name into an array of strings.

ds.split_qualifiers(:s) # ['s']
ds.split_qualifiers(Sequel[:t][:s]) # ['t', 's']
ds.split_qualifiers(Sequel[:d][:t][:s]) # ['d', 't', 's']
ds.split_qualifiers(Sequel.qualify(Sequel[:h][:d], Sequel[:t][:s])) # ['h', 'd', 't', 's']
    # File lib/sequel/dataset/sql.rb
722 def split_qualifiers(table_name, *args)
723   case table_name
724   when SQL::QualifiedIdentifier
725     split_qualifiers(table_name.table, nil) + split_qualifiers(table_name.column, nil)
726   else
727     sch, table = schema_and_table(table_name, *args)
728     sch ? [sch, table] : [table]
729   end
730 end
subscript_sql_append(sql, s) click to toggle source

Append literalization of subscripts (SQL array accesses) to SQL string.

    # File lib/sequel/dataset/sql.rb
733 def subscript_sql_append(sql, s)
734   case s.expression
735   when Symbol, SQL::Subscript, SQL::Identifier, SQL::QualifiedIdentifier
736     # nothing
737   else
738     wrap_expression = true
739     sql << '('
740   end
741   literal_append(sql, s.expression)
742   if wrap_expression
743     sql << ')['
744   else
745     sql << '['
746   end
747   sub = s.sub
748   if sub.length == 1 && (range = sub.first).is_a?(Range)
749     literal_append(sql, range.begin)
750     sql << ':'
751     e = range.end
752     e -= 1 if range.exclude_end? && e.is_a?(Integer)
753     literal_append(sql, e)
754   else
755     expression_list_append(sql, s.sub)
756   end
757   sql << ']'
758 end
window_sql_append(sql, opts) click to toggle source

Append literalization of windows (for window functions) to SQL string.

    # File lib/sequel/dataset/sql.rb
761 def window_sql_append(sql, opts)
762   raise(Error, 'This dataset does not support window functions') unless supports_window_functions?
763   space = false
764   space_s = ' '
765 
766   sql << '('
767 
768   if window = opts[:window]
769     literal_append(sql, window)
770     space = true
771   end
772 
773   if part = opts[:partition]
774     sql << space_s if space
775     sql << "PARTITION BY "
776     expression_list_append(sql, Array(part))
777     space = true
778   end
779 
780   if order = opts[:order]
781     sql << space_s if space
782     sql << "ORDER BY "
783     expression_list_append(sql, Array(order))
784     space = true
785   end
786 
787   if frame = opts[:frame]
788     sql << space_s if space
789 
790     if frame.is_a?(String)
791       sql << frame
792     else
793       case frame
794       when :all
795         frame_type = :rows
796         frame_start = :preceding
797         frame_end = :following
798       when :rows, :range, :groups
799         frame_type = frame
800         frame_start = :preceding
801         frame_end = :current
802       when Hash
803         frame_type = frame[:type]
804         unless frame_type == :rows || frame_type == :range || frame_type == :groups
805           raise Error, "invalid window :frame :type option: #{frame_type.inspect}"
806         end
807         unless frame_start = frame[:start]
808           raise Error, "invalid window :frame :start option: #{frame_start.inspect}"
809         end
810         frame_end = frame[:end]
811         frame_exclude = frame[:exclude]
812       else
813         raise Error, "invalid window :frame option: #{frame.inspect}"
814       end
815 
816       sql << frame_type.to_s.upcase << " "
817       sql << 'BETWEEN ' if frame_end
818       window_frame_boundary_sql_append(sql, frame_start, :preceding)
819       if frame_end
820         sql << " AND "
821         window_frame_boundary_sql_append(sql, frame_end, :following)
822       end
823 
824       if frame_exclude
825         sql << " EXCLUDE "
826 
827         case frame_exclude
828         when :current
829           sql << "CURRENT ROW"
830         when :group
831           sql << "GROUP"
832         when :ties
833           sql << "TIES"
834         when :no_others
835           sql << "NO OTHERS"
836         else
837           raise Error, "invalid window :frame :exclude option: #{frame_exclude.inspect}"
838         end
839       end
840     end
841   end
842 
843   sql << ')'
844 end

Protected Instance Methods

compound_from_self() click to toggle source

Return a from_self dataset if an order or limit is specified, so it works as expected with UNION, EXCEPT, and INTERSECT clauses.

    # File lib/sequel/dataset/sql.rb
850 def compound_from_self
851   (@opts[:sql] || @opts[:limit] || @opts[:order] || @opts[:offset]) ? from_self : self
852 end

Private Instance Methods

_check_modification_allowed!(modifying_joins_supported) click to toggle source

Internals of the check_*_allowed! methods

     # File lib/sequel/dataset/sql.rb
1026 def _check_modification_allowed!(modifying_joins_supported)
1027   raise(InvalidOperation, "Grouped datasets cannot be modified") if opts[:group]
1028   raise(InvalidOperation, "Joined datasets cannot be modified") if !modifying_joins_supported && joined_dataset?
1029 end
_insert_columns_sql(sql, columns) click to toggle source
     # File lib/sequel/dataset/sql.rb
1251 def _insert_columns_sql(sql, columns)
1252   if columns && !columns.empty?
1253     sql << ' ('
1254     identifier_list_append(sql, columns)
1255     sql << ')'
1256   end 
1257 end
_insert_values_sql(sql, values) click to toggle source
     # File lib/sequel/dataset/sql.rb
1273 def _insert_values_sql(sql, values)
1274   case values
1275   when Array
1276     if values.empty?
1277       sql << " DEFAULT VALUES"
1278     else
1279       sql << " VALUES "
1280       literal_append(sql, values)
1281     end
1282   when Dataset
1283     sql << ' '
1284     subselect_sql_append(sql, values)
1285   when LiteralString
1286     sql << ' ' << values
1287   else
1288     raise Error, "Unsupported INSERT values type, should be an Array or Dataset: #{values.inspect}"
1289   end
1290 end
_merge_delete_sql(sql, data) click to toggle source
    # File lib/sequel/dataset/sql.rb
869 def _merge_delete_sql(sql, data)
870   sql << " THEN DELETE"
871 end
_merge_insert_sql(sql, data) click to toggle source

Append the INSERT sql used in a MERGE

    # File lib/sequel/dataset/sql.rb
857 def _merge_insert_sql(sql, data)
858   sql << " THEN INSERT"
859   columns, values = _parse_insert_sql_args(data[:values])
860   _insert_columns_sql(sql, columns)
861   _insert_values_sql(sql, values)
862 end
_merge_update_sql(sql, data) click to toggle source
    # File lib/sequel/dataset/sql.rb
864 def _merge_update_sql(sql, data)
865   sql << " THEN UPDATE SET "
866   update_sql_values_hash(sql, data[:values])
867 end
_merge_when_conditions_sql(sql, data) click to toggle source

Append MERGE WHEN conditions, if there are conditions provided.

    # File lib/sequel/dataset/sql.rb
895 def _merge_when_conditions_sql(sql, data)
896   if data.has_key?(:conditions)
897     sql << " AND "
898     literal_append(sql, data[:conditions])
899   end
900 end
_merge_when_sql(sql) click to toggle source

Add the WHEN clauses to the MERGE SQL

    # File lib/sequel/dataset/sql.rb
884 def _merge_when_sql(sql)
885   raise Error, "no WHEN [NOT] MATCHED clauses provided for MERGE" unless merge_when = @opts[:merge_when]
886   merge_when.each do |data|
887     type = data[:type]
888     sql << MERGE_TYPE_SQL[type]
889     _merge_when_conditions_sql(sql, data)
890     send(:"_merge_#{type}_sql", sql, data)
891   end
892 end
_parse_insert_sql_args(values) click to toggle source

Parse the values passed to insert_sql, returning columns and values to use for the INSERT. Returned columns is always an array, but can be empty for an INSERT without explicit column references. Returned values can be an array, dataset, or literal string.

    # File lib/sequel/dataset/sql.rb
906 def _parse_insert_sql_args(values)
907   columns = []
908 
909   case values.size
910   when 0
911     values = []
912   when 1
913     case vals = values[0]
914     when Hash
915       values = []
916       vals.each do |k,v| 
917         columns << k
918         values << v
919       end
920     when Dataset, Array, LiteralString
921       values = vals
922     end
923   when 2
924     if (v0 = values[0]).is_a?(Array) && ((v1 = values[1]).is_a?(Array) || v1.is_a?(Dataset) || v1.is_a?(LiteralString))
925       columns, values = v0, v1
926       raise(Error, "Different number of values and columns given to insert_sql") if values.is_a?(Array) and columns.length != values.length
927     end
928   end
929 
930   [columns, values]
931 end
_truncate_sql(table) click to toggle source

Formats the truncate statement. Assumes the table given has already been literalized.

    # File lib/sequel/dataset/sql.rb
935 def _truncate_sql(table)
936   "TRUNCATE TABLE #{table}"
937 end
aggregate_dataset() click to toggle source

Clone of this dataset usable in aggregate operations. Does a from_self if dataset contains any parameters that would affect normal aggregation, or just removes an existing order if not. Also removes the row_proc, which isn't needed for aggregate calculations.

    # File lib/sequel/dataset/sql.rb
979 def aggregate_dataset
980   (options_overlap(COUNT_FROM_SELF_OPTS) ? from_self : unordered).naked
981 end
alias_alias_symbol(s) click to toggle source

Returns an appropriate symbol for the alias represented by s.

    # File lib/sequel/dataset/sql.rb
940 def alias_alias_symbol(s)
941   case s
942   when Symbol
943     s
944   when String
945     s.to_sym
946   when SQL::Identifier
947     s.value.to_s.to_sym
948   else
949     raise Error, "Invalid alias for alias_alias_symbol: #{s.inspect}"
950   end
951 end
alias_symbol(sym) click to toggle source

Returns an appropriate alias symbol for the given object, which can be a Symbol, String, SQL::Identifier, SQL::QualifiedIdentifier, or SQL::AliasedExpression.

    # File lib/sequel/dataset/sql.rb
956 def alias_symbol(sym)
957   case sym
958   when Symbol
959     s, t, a = split_symbol(sym)
960     a || s ? (a || t).to_sym : sym
961   when String
962     sym.to_sym
963   when SQL::Identifier
964     sym.value.to_s.to_sym
965   when SQL::QualifiedIdentifier
966     alias_symbol(sym.column)
967   when SQL::AliasedExpression
968     alias_alias_symbol(sym.alias)
969   else
970     raise Error, "Invalid alias for alias_symbol: #{sym.inspect}"
971   end
972 end
as_sql_append(sql, aliaz, column_aliases=nil) click to toggle source

Append aliasing expression to SQL string.

    # File lib/sequel/dataset/sql.rb
984 def as_sql_append(sql, aliaz, column_aliases=nil)
985   sql << ' AS '
986   quote_identifier_append(sql, aliaz)
987   if column_aliases
988     raise Error, "#{db.database_type} does not support derived column lists" unless supports_derived_column_lists?
989     sql << '('
990     identifier_list_append(sql, column_aliases)
991     sql << ')'
992   end
993 end
cache_sql?() click to toggle source

Don't allow caching SQL if specifically marked not to.

    # File lib/sequel/dataset/sql.rb
996 def cache_sql?
997   !@opts[:no_cache_sql] && !cache_get(:_no_cache_sql)
998 end
check_delete_allowed!() click to toggle source

Check whether it is allowed to delete from this dataset.

     # File lib/sequel/dataset/sql.rb
1016 def check_delete_allowed!
1017   _check_modification_allowed!(supports_deleting_joins?)
1018 end
check_insert_allowed!() click to toggle source

Check whether it is allowed to insert into this dataset.

     # File lib/sequel/dataset/sql.rb
1010 def check_insert_allowed!
1011   _check_modification_allowed!(false)
1012 end
Also aliased as: check_truncation_allowed!
check_modification_allowed!() click to toggle source

Raise an InvalidOperation exception if modification is not allowed for this dataset. Check whether it is allowed to insert into this dataset. Only for backwards compatibility with older external adapters.

     # File lib/sequel/dataset/sql.rb
1003 def check_modification_allowed!
1004   # SEQUEL6: Remove
1005   Sequel::Deprecation.deprecate("Dataset#check_modification_allowed!", "Use check_{insert,delete,update,truncation}_allowed! instead")
1006   _check_modification_allowed!(supports_modifying_joins?)
1007 end
check_not_limited!(type) click to toggle source

Raise error if the dataset uses limits or offsets.

     # File lib/sequel/dataset/sql.rb
1032 def check_not_limited!(type)
1033   return if @opts[:skip_limit_check] && type != :truncate
1034   raise InvalidOperation, "Dataset##{type} not supported on datasets with limits or offsets" if opts[:limit] || opts[:offset]
1035 end
check_truncation_allowed!()
check_update_allowed!() click to toggle source

Check whether it is allowed to update this dataset.

     # File lib/sequel/dataset/sql.rb
1021 def check_update_allowed!
1022   _check_modification_allowed!(supports_updating_joins?)
1023 end
column_list_append(sql, columns) click to toggle source

Append column list to SQL string. If the column list is empty, a wildcard (*) is appended.

     # File lib/sequel/dataset/sql.rb
1039 def column_list_append(sql, columns)
1040   if (columns.nil? || columns.empty?)
1041     sql << '*'
1042   else
1043     expression_list_append(sql, columns)
1044   end
1045 end
complex_expression_arg_pairs(args) { |args, args| ... } click to toggle source

Yield each pair of arguments to the block, which should return an object representing the SQL expression for those two arguments. For more than two arguments, the first argument to the block will be result of the previous block call.

     # File lib/sequel/dataset/sql.rb
1051 def complex_expression_arg_pairs(args)
1052   case args.length
1053   when 1
1054     args[0]
1055   when 2
1056     yield args[0], args[1]
1057   else
1058     args.inject{|m, a| yield(m, a)}
1059   end
1060 end
complex_expression_arg_pairs_append(sql, args, &block) click to toggle source

Append the literalization of the args using complex_expression_arg_pairs to the given SQL string, used when database operator/function is 2-ary where Sequel expression is N-ary.

     # File lib/sequel/dataset/sql.rb
1065 def complex_expression_arg_pairs_append(sql, args, &block)
1066   literal_append(sql, complex_expression_arg_pairs(args, &block))
1067 end
complex_expression_emulate_append(sql, op, args) click to toggle source

Append literalization of complex expression to SQL string, for operators unsupported by some databases. Used by adapters for databases that don't support the operators natively.

     # File lib/sequel/dataset/sql.rb
1072 def complex_expression_emulate_append(sql, op, args)
1073   # :nocov:
1074   case op
1075   # :nocov:
1076   when :%
1077     complex_expression_arg_pairs_append(sql, args){|a, b| Sequel.function(:MOD, a, b)}
1078   when :>>
1079     complex_expression_arg_pairs_append(sql, args){|a, b| Sequel./(a, Sequel.function(:power, 2, b))}
1080   when :<<
1081     complex_expression_arg_pairs_append(sql, args){|a, b| Sequel.*(a, Sequel.function(:power, 2, b))}
1082   when :&, :|, :^
1083     f = BITWISE_METHOD_MAP[op]
1084     complex_expression_arg_pairs_append(sql, args){|a, b| Sequel.function(f, a, b)}
1085   when :'B~'
1086     sql << "((0 - "
1087     literal_append(sql, args[0])
1088     sql << ") - 1)"
1089   end
1090 end
compound_dataset_sql_append(sql, ds) click to toggle source

Append literalization of dataset used in UNION/INTERSECT/EXCEPT clause to SQL string.

     # File lib/sequel/dataset/sql.rb
1093 def compound_dataset_sql_append(sql, ds)
1094   subselect_sql_append(sql, ds)
1095 end
dataset_alias(number) click to toggle source

The alias to use for datasets, takes a number to make sure the name is unique.

     # File lib/sequel/dataset/sql.rb
1098 def dataset_alias(number)
1099   :"t#{number}"
1100 end
default_timestamp_format() click to toggle source

The strftime format to use when literalizing the time.

     # File lib/sequel/dataset/sql.rb
1103 def default_timestamp_format
1104   requires_sql_standard_datetimes? ? "TIMESTAMP '%Y-%m-%d %H:%M:%S%N%z'" : "'%Y-%m-%d %H:%M:%S%N%z'"
1105 end
delete_delete_sql(sql) click to toggle source
     # File lib/sequel/dataset/sql.rb
1107 def delete_delete_sql(sql)
1108   sql << 'DELETE'
1109 end
delete_from_sql(sql) click to toggle source
     # File lib/sequel/dataset/sql.rb
1111 def delete_from_sql(sql)
1112   if f = @opts[:from]
1113     sql << ' FROM '
1114     source_list_append(sql, f)
1115   end
1116 end
delete_order_sql(sql)
Alias for: select_order_sql
delete_returning_sql(sql)
delete_where_sql(sql)
Alias for: select_where_sql
delete_with_sql(sql)
Alias for: select_with_sql
disable_sql_caching!() click to toggle source

Disable caching of SQL for the current dataset

     # File lib/sequel/dataset/sql.rb
1119 def disable_sql_caching!
1120   cache_set(:_no_cache_sql, true)
1121 end
empty_array_value(op, cols) click to toggle source

An expression for how to handle an empty array lookup.

     # File lib/sequel/dataset/sql.rb
1163 def empty_array_value(op, cols)
1164   {1 => ((op == :IN) ? 0 : 1)}
1165 end
empty_from_sql() click to toggle source

An SQL FROM clause to use in SELECT statements where the dataset has no from tables.

     # File lib/sequel/dataset/sql.rb
1125 def empty_from_sql
1126   nil
1127 end
emulate_function?(name) click to toggle source

Whether to emulate the function with the given name. This should only be true if the emulation goes beyond choosing a function with a different name.

     # File lib/sequel/dataset/sql.rb
1131 def emulate_function?(name)
1132   false
1133 end
expression_list_append(sql, columns) click to toggle source

Append literalization of array of expressions to SQL string, separating them with commas.

     # File lib/sequel/dataset/sql.rb
1137 def expression_list_append(sql, columns)
1138   c = false
1139   co = ', '
1140   columns.each do |col|
1141     sql << co if c
1142     literal_append(sql, col)
1143     c ||= true
1144   end
1145 end
format_timestamp(v) click to toggle source

Format the timestamp based on the default_timestamp_format, with a couple of modifiers. First, allow %N to be used for fractions seconds (if the database supports them), and override %z to always use a numeric offset of hours and minutes.

     # File lib/sequel/dataset/sql.rb
1171 def format_timestamp(v)
1172   v2 = db.from_application_timestamp(v)
1173   fmt = default_timestamp_format.gsub(/%[Nz]/) do |m|
1174     if m == '%N'
1175       # Ruby 1.9 supports %N in timestamp formats, but Sequel has supported %N
1176       # for longer in a different way, where the . is already appended and only 6
1177       # decimal places are used by default.
1178       format_timestamp_usec(v.is_a?(DateTime) ? v.sec_fraction*(1000000) : v.usec) if supports_timestamp_usecs?
1179     else
1180       if supports_timestamp_timezones?
1181         # Would like to just use %z format, but it doesn't appear to work on Windows
1182         # Instead, the offset fragment is constructed manually
1183         minutes = (v2.is_a?(DateTime) ? v2.offset * 1440 : v2.utc_offset/60).to_i
1184         format_timestamp_offset(*minutes.divmod(60))
1185       end
1186     end
1187   end
1188   v2.strftime(fmt)
1189 end
format_timestamp_offset(hour, minute) click to toggle source

Return the SQL timestamp fragment to use for the timezone offset.

     # File lib/sequel/dataset/sql.rb
1192 def format_timestamp_offset(hour, minute)
1193   sprintf("%+03i%02i", hour, minute)
1194 end
format_timestamp_usec(usec, ts=timestamp_precision) click to toggle source

Return the SQL timestamp fragment to use for the fractional time part. Should start with the decimal point. Uses 6 decimal places by default.

     # File lib/sequel/dataset/sql.rb
1198 def format_timestamp_usec(usec, ts=timestamp_precision)
1199   unless ts == 6
1200     usec = usec/(10 ** (6 - ts))
1201   end
1202   sprintf(".%0#{ts}d", usec)
1203 end
grouping_element_list_append(sql, columns) click to toggle source

Append literalization of array of grouping elements to SQL string, seperating them with commas.

     # File lib/sequel/dataset/sql.rb
1148 def grouping_element_list_append(sql, columns)
1149   c = false
1150   co = ', '
1151   columns.each do |col|
1152     sql << co if c
1153     if col.is_a?(Array) && col.empty?
1154       sql << '()'
1155     else
1156       literal_append(sql, Array(col))
1157     end
1158     c ||= true
1159   end
1160 end
identifier_append(sql, v) click to toggle source

Append literalization of identifier to SQL string, considering regular strings as SQL identifiers instead of SQL strings.

     # File lib/sequel/dataset/sql.rb
1207 def identifier_append(sql, v)
1208   if v.is_a?(String)
1209     case v
1210     when LiteralString
1211       sql << v
1212     when SQL::Blob
1213       literal_append(sql, v)
1214     else
1215       quote_identifier_append(sql, v)
1216     end
1217   else
1218     literal_append(sql, v)
1219   end
1220 end
identifier_list_append(sql, args) click to toggle source

Append literalization of array of identifiers to SQL string.

     # File lib/sequel/dataset/sql.rb
1223 def identifier_list_append(sql, args)
1224   c = false
1225   comma = ', '
1226   args.each do |a|
1227     sql << comma if c
1228     identifier_append(sql, a)
1229     c ||= true
1230   end
1231 end
input_identifier(v) click to toggle source

Upcase identifiers by default when inputting them into the database.

     # File lib/sequel/dataset/sql.rb
1234 def input_identifier(v)
1235   v.to_s.upcase
1236 end
insert_columns_sql(sql) click to toggle source
     # File lib/sequel/dataset/sql.rb
1247 def insert_columns_sql(sql)
1248   _insert_columns_sql(sql, opts[:columns])
1249 end
insert_empty_columns_values() click to toggle source

The columns and values to use for an empty insert if the database doesn't support INSERT with DEFAULT VALUES.

     # File lib/sequel/dataset/sql.rb
1261 def insert_empty_columns_values
1262   [[columns.last], [DEFAULT]]
1263 end
insert_insert_sql(sql) click to toggle source
     # File lib/sequel/dataset/sql.rb
1265 def insert_insert_sql(sql)
1266   sql << "INSERT"
1267 end
insert_into_sql(sql) click to toggle source
     # File lib/sequel/dataset/sql.rb
1238 def insert_into_sql(sql)
1239   sql << " INTO "
1240   if (f = @opts[:from]) && f.length == 1
1241     identifier_append(sql, unaliased_identifier(f.first))
1242   else
1243     source_list_append(sql, f)
1244   end
1245 end
insert_returning_sql(sql) click to toggle source
     # File lib/sequel/dataset/sql.rb
1292 def insert_returning_sql(sql)
1293   if opts.has_key?(:returning)
1294     sql << " RETURNING "
1295     column_list_append(sql, Array(opts[:returning]))
1296   end
1297 end
insert_values_sql(sql) click to toggle source
     # File lib/sequel/dataset/sql.rb
1269 def insert_values_sql(sql)
1270   _insert_values_sql(sql, opts[:values])
1271 end
insert_with_sql(sql)
Alias for: select_with_sql
join_type_sql(join_type) click to toggle source

SQL fragment specifying a JOIN type, converts underscores to spaces and upcases.

     # File lib/sequel/dataset/sql.rb
1303 def join_type_sql(join_type)
1304   "#{join_type.to_s.gsub('_', ' ').upcase} JOIN"
1305 end
join_using_clause_using_sql_append(sql, using_columns) click to toggle source

Append USING clause for JOIN USING

     # File lib/sequel/dataset/sql.rb
1308 def join_using_clause_using_sql_append(sql, using_columns)
1309   sql << ' USING ('
1310   column_list_append(sql, using_columns)
1311   sql << ')'
1312 end
literal_array_append(sql, v) click to toggle source

Append a literalization of the array to SQL string. Treats as an expression if an array of all two pairs, or as a SQL array otherwise.

     # File lib/sequel/dataset/sql.rb
1316 def literal_array_append(sql, v)
1317   if Sequel.condition_specifier?(v)
1318     literal_expression_append(sql, SQL::BooleanExpression.from_value_pairs(v))
1319   else
1320     array_sql_append(sql, v)
1321   end
1322 end
literal_big_decimal(v) click to toggle source

SQL fragment for BigDecimal

     # File lib/sequel/dataset/sql.rb
1325 def literal_big_decimal(v)
1326   d = v.to_s("F")
1327   v.nan? || v.infinite? ?  "'#{d}'" : d
1328 end
literal_blob_append(sql, v) click to toggle source

Append literalization of SQL::Blob to SQL string.

     # File lib/sequel/dataset/sql.rb
1331 def literal_blob_append(sql, v)
1332   literal_string_append(sql, v)
1333 end
literal_dataset_append(sql, v) click to toggle source

Append literalization of dataset to SQL string. Does a subselect inside parantheses.

     # File lib/sequel/dataset/sql.rb
1336 def literal_dataset_append(sql, v)
1337   sql << 'LATERAL ' if v.opts[:lateral]
1338   sql << '('
1339   subselect_sql_append(sql, v)
1340   sql << ')'
1341 end
literal_date(v) click to toggle source

SQL fragment for Date, using the ISO8601 format.

     # File lib/sequel/dataset/sql.rb
1344 def literal_date(v)
1345   if requires_sql_standard_datetimes?
1346     v.strftime("DATE '%Y-%m-%d'")
1347   else
1348     v.strftime("'%Y-%m-%d'")
1349   end
1350 end
literal_datetime(v) click to toggle source

SQL fragment for DateTime

     # File lib/sequel/dataset/sql.rb
1353 def literal_datetime(v)
1354   format_timestamp(v)
1355 end
literal_datetime_append(sql, v) click to toggle source

Append literalization of DateTime to SQL string.

     # File lib/sequel/dataset/sql.rb
1358 def literal_datetime_append(sql, v)
1359   sql << literal_datetime(v)
1360 end
literal_expression_append(sql, v) click to toggle source

Append literalization of SQL::Expression to SQL string.

     # File lib/sequel/dataset/sql.rb
1363 def literal_expression_append(sql, v)
1364   v.to_s_append(self, sql)
1365 end
literal_false() click to toggle source

SQL fragment for false

     # File lib/sequel/dataset/sql.rb
1368 def literal_false
1369   "'f'"
1370 end
literal_float(v) click to toggle source

SQL fragment for Float

     # File lib/sequel/dataset/sql.rb
1373 def literal_float(v)
1374   v.to_s
1375 end
literal_hash_append(sql, v) click to toggle source

Append literalization of Hash to SQL string, treating hash as a boolean expression.

     # File lib/sequel/dataset/sql.rb
1378 def literal_hash_append(sql, v)
1379   literal_expression_append(sql, SQL::BooleanExpression.from_value_pairs(v))
1380 end
literal_integer(v) click to toggle source

SQL fragment for Integer

     # File lib/sequel/dataset/sql.rb
1383 def literal_integer(v)
1384   v.to_s
1385 end
literal_nil() click to toggle source

SQL fragment for nil

     # File lib/sequel/dataset/sql.rb
1388 def literal_nil
1389   "NULL"
1390 end
literal_other_append(sql, v) click to toggle source

Append a literalization of the object to the given SQL string. Calls sql_literal_append if object responds to it, otherwise calls sql_literal if object responds to it, otherwise raises an error. If a database specific type is allowed, this should be overriden in a subclass.

     # File lib/sequel/dataset/sql.rb
1396 def literal_other_append(sql, v)
1397   # We can't be sure if v will always literalize to the same SQL, so
1398   # don't cache SQL for a dataset that uses this.
1399   disable_sql_caching!
1400 
1401   if v.respond_to?(:sql_literal_append)
1402     v.sql_literal_append(self, sql)
1403   elsif v.respond_to?(:sql_literal)
1404     sql << v.sql_literal(self)
1405   else
1406     raise Error, "can't express #{v.inspect} as a SQL literal"
1407   end
1408 end
literal_sqltime(v) click to toggle source

SQL fragment for Sequel::SQLTime, containing just the time part

     # File lib/sequel/dataset/sql.rb
1411 def literal_sqltime(v)
1412   v.strftime("'%H:%M:%S#{format_timestamp_usec(v.usec, sqltime_precision) if supports_timestamp_usecs?}'")
1413 end
literal_sqltime_append(sql, v) click to toggle source

Append literalization of Sequel::SQLTime to SQL string.

     # File lib/sequel/dataset/sql.rb
1416 def literal_sqltime_append(sql, v)
1417   sql << literal_sqltime(v)
1418 end
literal_string_append(sql, v) click to toggle source

Append literalization of string to SQL string.

     # File lib/sequel/dataset/sql.rb
1421 def literal_string_append(sql, v)
1422   sql << "'" << v.gsub("'", "''") << "'"
1423 end
literal_symbol_append(sql, v) click to toggle source

Append literalization of symbol to SQL string.

     # File lib/sequel/dataset/sql.rb
1426 def literal_symbol_append(sql, v)
1427   c_table, column, c_alias = split_symbol(v)
1428   if c_table
1429     quote_identifier_append(sql, c_table)
1430     sql << '.'
1431   end
1432   quote_identifier_append(sql, column)
1433   as_sql_append(sql, c_alias) if c_alias
1434 end
literal_time(v) click to toggle source

SQL fragment for Time

     # File lib/sequel/dataset/sql.rb
1437 def literal_time(v)
1438   format_timestamp(v)
1439 end
literal_time_append(sql, v) click to toggle source

Append literalization of Time to SQL string.

     # File lib/sequel/dataset/sql.rb
1442 def literal_time_append(sql, v)
1443   sql << literal_time(v)
1444 end
literal_true() click to toggle source

SQL fragment for true

     # File lib/sequel/dataset/sql.rb
1447 def literal_true
1448   "'t'"
1449 end
multi_insert_sql_strategy() click to toggle source

What strategy to use for import/multi_insert. While SQL-92 defaults to allowing multiple rows in a VALUES clause, there are enough databases that don't allow that that it can't be the default. Use separate queries by default, which works everywhere.

     # File lib/sequel/dataset/sql.rb
1455 def multi_insert_sql_strategy
1456   :separate
1457 end
native_function_name(emulated_function) click to toggle source

Get the native function name given the emulated function name.

     # File lib/sequel/dataset/sql.rb
1461 def native_function_name(emulated_function)
1462   emulated_function
1463 end
qualified_column_name(column, table) click to toggle source

Returns a qualified column name (including a table name) if the column name isn't already qualified.

     # File lib/sequel/dataset/sql.rb
1467 def qualified_column_name(column, table)
1468   if column.is_a?(Symbol)
1469     c_table, column, _ = split_symbol(column)
1470     unless c_table
1471       case table
1472       when Symbol
1473         schema, table, t_alias = split_symbol(table)
1474         t_alias ||= Sequel::SQL::QualifiedIdentifier.new(schema, table) if schema
1475       when Sequel::SQL::AliasedExpression
1476         t_alias = table.alias
1477       end
1478       c_table = t_alias || table
1479     end
1480     ::Sequel::SQL::QualifiedIdentifier.new(c_table, column)
1481   else
1482     column
1483   end
1484 end
qualified_expression(e, table) click to toggle source

Qualify the given expression to the given table.

     # File lib/sequel/dataset/sql.rb
1487 def qualified_expression(e, table)
1488   Qualifier.new(table).transform(e)
1489 end
select_columns_sql(sql) click to toggle source
     # File lib/sequel/dataset/sql.rb
1491 def select_columns_sql(sql)
1492   sql << ' '
1493   column_list_append(sql, @opts[:select])
1494 end
select_compounds_sql(sql) click to toggle source

Modify the sql to add a dataset to the via an EXCEPT, INTERSECT, or UNION clause. This uses a subselect for the compound datasets used, because using parantheses doesn't work on all databases.

     # File lib/sequel/dataset/sql.rb
1510 def select_compounds_sql(sql)
1511   return unless c = @opts[:compounds]
1512   c.each do |type, dataset, all|
1513     sql << ' ' << type.to_s.upcase
1514     sql << ' ALL' if all
1515     sql << ' '
1516     compound_dataset_sql_append(sql, dataset)
1517   end
1518 end
select_distinct_sql(sql) click to toggle source
     # File lib/sequel/dataset/sql.rb
1496 def select_distinct_sql(sql)
1497   if distinct = @opts[:distinct]
1498     sql << " DISTINCT"
1499     unless distinct.empty?
1500       sql << " ON ("
1501       expression_list_append(sql, distinct)
1502       sql << ')'
1503     end
1504   end
1505 end
select_from_sql(sql) click to toggle source
     # File lib/sequel/dataset/sql.rb
1520 def select_from_sql(sql)
1521   if f = @opts[:from]
1522     sql << ' FROM '
1523     source_list_append(sql, f)
1524   elsif f = empty_from_sql
1525     sql << f
1526   end
1527 end
select_group_sql(sql) click to toggle source
     # File lib/sequel/dataset/sql.rb
1529 def select_group_sql(sql)
1530   if group = @opts[:group]
1531     sql << " GROUP BY "
1532     if go = @opts[:group_options]
1533       if go == :"grouping sets"
1534         sql << go.to_s.upcase << '('
1535         grouping_element_list_append(sql, group)
1536         sql << ')'
1537       elsif uses_with_rollup?
1538         expression_list_append(sql, group)
1539         sql << " WITH " << go.to_s.upcase
1540       else
1541         sql << go.to_s.upcase << '('
1542         expression_list_append(sql, group)
1543         sql << ')'
1544       end
1545     else
1546       expression_list_append(sql, group)
1547     end
1548   end
1549 end
select_having_sql(sql) click to toggle source
     # File lib/sequel/dataset/sql.rb
1551 def select_having_sql(sql)
1552   if having = @opts[:having]
1553     sql << " HAVING "
1554     literal_append(sql, having)
1555   end
1556 end
select_join_sql(sql) click to toggle source
     # File lib/sequel/dataset/sql.rb
1558 def select_join_sql(sql)
1559   if js = @opts[:join]
1560     js.each{|j| literal_append(sql, j)}
1561   end
1562 end
select_limit_sql(sql) click to toggle source
     # File lib/sequel/dataset/sql.rb
1564 def select_limit_sql(sql)
1565   if l = @opts[:limit]
1566     sql << " LIMIT "
1567     literal_append(sql, l)
1568     if o = @opts[:offset]
1569       sql << " OFFSET "
1570       literal_append(sql, o)
1571     end
1572   elsif @opts[:offset]
1573     select_only_offset_sql(sql)
1574   end
1575 end
select_lock_sql(sql) click to toggle source
     # File lib/sequel/dataset/sql.rb
1577 def select_lock_sql(sql)
1578   case l = @opts[:lock]
1579   when :update
1580     sql << ' FOR UPDATE'
1581   when String
1582     sql << ' ' << l
1583   end
1584 end
select_only_offset_sql(sql) click to toggle source

Used only if there is an offset and no limit, making it easier to override in the adapter, as many databases do not support just a plain offset with no limit.

     # File lib/sequel/dataset/sql.rb
1589 def select_only_offset_sql(sql)
1590   sql << " OFFSET "
1591   literal_append(sql, @opts[:offset])
1592 end
select_order_sql(sql) click to toggle source
     # File lib/sequel/dataset/sql.rb
1594 def select_order_sql(sql)
1595   if o = @opts[:order]
1596     sql << " ORDER BY "
1597     expression_list_append(sql, o)
1598   end
1599 end
select_select_sql(sql) click to toggle source
     # File lib/sequel/dataset/sql.rb
1603 def select_select_sql(sql)
1604   sql << 'SELECT'
1605 end
select_where_sql(sql) click to toggle source
     # File lib/sequel/dataset/sql.rb
1607 def select_where_sql(sql)
1608   if w = @opts[:where]
1609     sql << " WHERE "
1610     literal_append(sql, w)
1611   end
1612 end
select_window_sql(sql) click to toggle source
     # File lib/sequel/dataset/sql.rb
1616 def select_window_sql(sql)
1617   if ws = @opts[:window]
1618     sql << " WINDOW "
1619     c = false
1620     co = ', '
1621     as = ' AS '
1622     ws.map do |name, window|
1623       sql << co if c
1624       literal_append(sql, name)
1625       sql << as
1626       literal_append(sql, window)
1627       c ||= true
1628     end
1629   end
1630 end
select_with_sql(sql) click to toggle source
     # File lib/sequel/dataset/sql.rb
1632 def select_with_sql(sql)
1633   return unless supports_cte?
1634   ctes = opts[:with]
1635   return if !ctes || ctes.empty?
1636   sql << select_with_sql_base
1637   c = false
1638   comma = ', '
1639   ctes.each do |cte|
1640     sql << comma if c
1641     select_with_sql_cte(sql, cte)
1642     c ||= true
1643   end
1644   sql << ' '
1645 end
select_with_sql_base() click to toggle source
     # File lib/sequel/dataset/sql.rb
1650 def select_with_sql_base
1651   "WITH "
1652 end
select_with_sql_cte(sql, cte) click to toggle source
     # File lib/sequel/dataset/sql.rb
1654 def select_with_sql_cte(sql, cte)
1655   select_with_sql_prefix(sql, cte)
1656   literal_dataset_append(sql, cte[:dataset])
1657 end
select_with_sql_prefix(sql, w) click to toggle source
     # File lib/sequel/dataset/sql.rb
1659 def select_with_sql_prefix(sql, w)
1660   quote_identifier_append(sql, w[:name])
1661   if args = w[:args]
1662    sql << '('
1663    identifier_list_append(sql, args)
1664    sql << ')'
1665   end
1666   sql << ' AS '
1667 
1668   case w[:materialized]
1669   when true
1670     sql << "MATERIALIZED "
1671   when false
1672     sql << "NOT MATERIALIZED "
1673   end
1674 end
skip_symbol_cache?() click to toggle source

Whether the symbol cache should be skipped when literalizing the dataset

     # File lib/sequel/dataset/sql.rb
1677 def skip_symbol_cache?
1678   @opts[:skip_symbol_cache]
1679 end
source_list_append(sql, sources) click to toggle source

Append literalization of array of sources/tables to SQL string, raising an Error if there are no sources.

     # File lib/sequel/dataset/sql.rb
1683 def source_list_append(sql, sources)
1684   raise(Error, 'No source specified for query') if sources.nil? || sources == []
1685   identifier_list_append(sql, sources)
1686 end
split_symbol(sym) click to toggle source

Delegate to Sequel.split_symbol.

     # File lib/sequel/dataset/sql.rb
1689 def split_symbol(sym)
1690   Sequel.split_symbol(sym)
1691 end
sql_string_origin() click to toggle source

The string that is appended to to create the SQL query, the empty string by default.

     # File lib/sequel/dataset/sql.rb
1695 def sql_string_origin
1696   String.new
1697 end
sqltime_precision() click to toggle source

The precision to use for SQLTime instances (time column values without dates). Defaults to timestamp_precision.

     # File lib/sequel/dataset/sql.rb
1701 def sqltime_precision
1702   timestamp_precision
1703 end
static_sql(sql) click to toggle source

SQL to use if this dataset uses static SQL. Since static SQL can be a PlaceholderLiteralString in addition to a String, we literalize nonstrings. If there is an append_sql for this dataset, append to that SQL instead of returning the value.

     # File lib/sequel/dataset/sql.rb
1709 def static_sql(sql)
1710   if append_sql = @opts[:append_sql]
1711     if sql.is_a?(String)
1712       append_sql << sql
1713     else
1714       literal_append(append_sql, sql)
1715     end
1716   else
1717     if sql.is_a?(String)
1718       sql
1719     else
1720       literal(sql)
1721     end
1722   end
1723 end
subselect_sql_append(sql, ds) click to toggle source

Append literalization of the subselect to SQL string.

     # File lib/sequel/dataset/sql.rb
1726 def subselect_sql_append(sql, ds)
1727   sds = subselect_sql_dataset(sql, ds)
1728   sds.sql
1729   unless sds.send(:cache_sql?)
1730     # If subquery dataset does not allow caching SQL,
1731     # then this dataset should not allow caching SQL.
1732     disable_sql_caching!
1733   end
1734 end
subselect_sql_dataset(sql, ds) click to toggle source
     # File lib/sequel/dataset/sql.rb
1736 def subselect_sql_dataset(sql, ds)
1737   ds.clone(:append_sql=>sql)
1738 end
timestamp_precision() click to toggle source

The number of decimal digits of precision to use in timestamps.

     # File lib/sequel/dataset/sql.rb
1741 def timestamp_precision
1742   supports_timestamp_usecs? ? 6 : 0
1743 end
update_order_sql(sql)
Alias for: select_order_sql
update_returning_sql(sql)
update_set_sql(sql) click to toggle source
     # File lib/sequel/dataset/sql.rb
1751 def update_set_sql(sql)
1752   sql << ' SET '
1753   values = @opts[:values]
1754   if values.is_a?(Hash)
1755     update_sql_values_hash(sql, values)
1756   else
1757     sql << values
1758   end
1759 end
update_sql_values_hash(sql, values) click to toggle source
     # File lib/sequel/dataset/sql.rb
1761 def update_sql_values_hash(sql, values)
1762   c = false
1763   eq = ' = '
1764   values.each do |k, v|
1765     sql << ', ' if c
1766     if k.is_a?(String) && !k.is_a?(LiteralString)
1767       quote_identifier_append(sql, k)
1768     else
1769       literal_append(sql, k)
1770     end
1771     sql << eq
1772     literal_append(sql, v)
1773     c ||= true
1774   end
1775 end
update_table_sql(sql) click to toggle source
     # File lib/sequel/dataset/sql.rb
1745 def update_table_sql(sql)
1746   sql << ' '
1747   source_list_append(sql, @opts[:from])
1748   select_join_sql(sql) if supports_modifying_joins?
1749 end
update_update_sql(sql) click to toggle source
     # File lib/sequel/dataset/sql.rb
1777 def update_update_sql(sql)
1778   sql << 'UPDATE'
1779 end
update_where_sql(sql)
Alias for: select_where_sql
update_with_sql(sql)
Alias for: select_with_sql
window_frame_boundary_sql_append(sql, boundary, direction) click to toggle source
     # File lib/sequel/dataset/sql.rb
1781 def window_frame_boundary_sql_append(sql, boundary, direction)
1782   case boundary
1783   when :current
1784    sql << "CURRENT ROW"
1785   when :preceding
1786     sql << "UNBOUNDED PRECEDING"
1787   when :following
1788     sql << "UNBOUNDED FOLLOWING"
1789   else
1790     if boundary.is_a?(Array)
1791       offset, direction = boundary
1792       unless boundary.length == 2 && (direction == :preceding || direction == :following)
1793         raise Error, "invalid window :frame boundary (:start or :end) option: #{boundary.inspect}"
1794       end
1795     else
1796       offset = boundary
1797     end
1798 
1799     case offset
1800     when Numeric, String, SQL::Cast
1801       # nothing
1802     else
1803       raise Error, "invalid window :frame boundary (:start or :end) option: #{boundary.inspect}"
1804     end
1805 
1806     literal_append(sql, offset)
1807     sql << (direction == :preceding ? " PRECEDING" : " FOLLOWING")
1808   end
1809 end