Module | Sequel::MSSQL::DatasetMethods |
In: |
lib/sequel/adapters/shared/mssql.rb
|
BOOL_TRUE | = | '1'.freeze |
BOOL_FALSE | = | '0'.freeze |
COMMA_SEPARATOR | = | ', '.freeze |
DELETE_CLAUSE_METHODS | = | Dataset.clause_methods(:delete, %w'with from output from2 where') |
INSERT_CLAUSE_METHODS | = | Dataset.clause_methods(:insert, %w'with into columns output values') |
SELECT_CLAUSE_METHODS | = | Dataset.clause_methods(:select, %w'with distinct limit columns into from lock join where group having order compounds') |
UPDATE_CLAUSE_METHODS | = | Dataset.clause_methods(:update, %w'with table set output from where') |
NOLOCK | = | ' WITH (NOLOCK)'.freeze |
UPDLOCK | = | ' WITH (UPDLOCK)'.freeze |
WILDCARD | = | LiteralString.new('*').freeze |
CONSTANT_MAP | = | {:CURRENT_DATE=>'CAST(CURRENT_TIMESTAMP AS DATE)'.freeze, :CURRENT_TIME=>'CAST(CURRENT_TIMESTAMP AS TIME)'.freeze} |
mssql_unicode_strings | [RW] | Allow overriding of the mssql_unicode_strings option at the dataset level. |
Copy the mssql_unicode_strings option from the db object.
# File lib/sequel/adapters/shared/mssql.rb, line 250 250: def initialize(db, opts={}) 251: super 252: @mssql_unicode_strings = db.mssql_unicode_strings 253: end
Ugly hack. While MSSQL supports TRUE and FALSE values, you can‘t actually specify them directly in SQL. Unfortunately, you also cannot use an integer value when a boolean is required. Also unforunately, you cannot use an expression that yields a boolean type in cases where in an integer type is needed, such as inserting into a bit field (the closest thing MSSQL has to a boolean).
In filters, SQL::BooleanConstants are used more, while in other places the ruby true/false values are used more, so use expressions that return booleans for SQL::BooleanConstants, and 1/0 for other places. The correct fix for this would require separate literalization paths for filters compared to other values, but that‘s more work than I want to do right now.
# File lib/sequel/adapters/shared/mssql.rb, line 267 267: def boolean_constant_sql(constant) 268: case constant 269: when true 270: '(1 = 1)' 271: when false 272: '(1 = 0)' 273: else 274: super 275: end 276: end
MSSQL uses + for string concatenation, and LIKE is case insensitive by default.
# File lib/sequel/adapters/shared/mssql.rb, line 279 279: def complex_expression_sql(op, args) 280: case op 281: when '||''||' 282: super(:+, args) 283: when :ILIKE 284: super(:LIKE, args) 285: when "NOT ILIKE""NOT ILIKE" 286: super("NOT LIKE""NOT LIKE", args) 287: when :<< 288: "(#{literal(args[0])} * POWER(2, #{literal(args[1])}))" 289: when :>> 290: "(#{literal(args[0])} / POWER(2, #{literal(args[1])}))" 291: else 292: super(op, args) 293: end 294: end
Disable the use of INSERT OUTPUT
# File lib/sequel/adapters/shared/mssql.rb, line 302 302: def disable_insert_output 303: clone(:disable_insert_output=>true) 304: end
Disable the use of INSERT OUTPUT, modifying the receiver
# File lib/sequel/adapters/shared/mssql.rb, line 307 307: def disable_insert_output! 308: mutation_method(:disable_insert_output) 309: end
When returning all rows, if an offset is used, delete the row_number column before yielding the row.
# File lib/sequel/adapters/shared/mssql.rb, line 313 313: def fetch_rows(sql, &block) 314: @opts[:offset] ? super(sql){|r| r.delete(row_number_column); yield r} : super(sql, &block) 315: end
Use the OUTPUT clause to get the value of all columns for the newly inserted record.
# File lib/sequel/adapters/shared/mssql.rb, line 323 323: def insert_select(*values) 324: return unless supports_insert_select? 325: naked.clone(default_server_opts(:sql=>output(nil, [SQL::ColumnAll.new(:inserted)]).insert_sql(*values))).single_record 326: end
Specify a table for a SELECT … INTO query.
# File lib/sequel/adapters/shared/mssql.rb, line 329 329: def into(table) 330: clone(:into => table) 331: end
SQL Server does not support CTEs on subqueries, so move any CTEs on joined datasets to the top level. The user is responsible for resolving any name clashes this may cause.
# File lib/sequel/adapters/shared/mssql.rb, line 336 336: def join_table(type, table, expr=nil, table_alias={}, &block) 337: return super unless Dataset === table && table.opts[:with] 338: clone(:with => (opts[:with] || []) + table.opts[:with]).join_table(type, table.clone(:with => nil), expr, table_alias, &block) 339: end
Allows you to do a dirty read of uncommitted data using WITH (NOLOCK).
# File lib/sequel/adapters/shared/mssql.rb, line 347 347: def nolock 348: lock_style(:dirty) 349: end
Include an OUTPUT clause in the eventual INSERT, UPDATE, or DELETE query.
The first argument is the table to output into, and the second argument is either an Array of column values to select, or a Hash which maps output column names to selected values, in the style of insert or update.
Output into a returned result set is not currently supported.
Examples:
dataset.output(:output_table, [:deleted__id, :deleted__name]) dataset.output(:output_table, :id => :inserted__id, :name => :inserted__name)
# File lib/sequel/adapters/shared/mssql.rb, line 363 363: def output(into, values) 364: raise(Error, "SQL Server versions 2000 and earlier do not support the OUTPUT clause") unless supports_output_clause? 365: output = {} 366: case values 367: when Hash 368: output[:column_list], output[:select_list] = values.keys, values.values 369: when Array 370: output[:select_list] = values 371: end 372: output[:into] = into 373: clone({:output => output}) 374: end
MSSQL Requires the use of the ROW_NUMBER window function to emulate an offset. This implementation requires MSSQL 2005 or greater (offset can‘t be emulated well in MSSQL 2000).
The implementation is ugly, cloning the current dataset and modifying the clone to add a ROW_NUMBER window function (and some other things), then using the modified clone in a subselect which is selected from.
If offset is used, an order must be provided, because the use of ROW_NUMBER requires an order.
# File lib/sequel/adapters/shared/mssql.rb, line 396 396: def select_sql 397: return super unless o = @opts[:offset] 398: raise(Error, 'MSSQL requires an order be provided if using an offset') unless order = @opts[:order] 399: dsa1 = dataset_alias(1) 400: rn = row_number_column 401: subselect_sql(unlimited. 402: unordered. 403: select_append{ROW_NUMBER(:over, :order=>order){}.as(rn)}. 404: from_self(:alias=>dsa1). 405: limit(@opts[:limit]). 406: where(SQL::Identifier.new(rn) > o)) 407: end
The version of the database server.
# File lib/sequel/adapters/shared/mssql.rb, line 410 410: def server_version 411: db.server_version(@opts[:server]) 412: end
MSSQL supports insert_select via the OUTPUT clause.
# File lib/sequel/adapters/shared/mssql.rb, line 415 415: def supports_insert_select? 416: supports_output_clause? && !opts[:disable_insert_output] 417: end