Module Sequel::SQLite::DatasetMethods
In: lib/sequel/adapters/shared/sqlite.rb

Instance methods for datasets that connect to an SQLite database

Methods

Constants

SELECT_CLAUSE_METHODS = Dataset.clause_methods(:select, %w'select distinct columns from join where group having compounds order limit')
CONSTANT_MAP = {:CURRENT_DATE=>"date(CURRENT_TIMESTAMP, 'localtime')".freeze, :CURRENT_TIMESTAMP=>"datetime(CURRENT_TIMESTAMP, 'localtime')".freeze, :CURRENT_TIME=>"time(CURRENT_TIMESTAMP, 'localtime')".freeze}
EXTRACT_MAP = {:year=>"'%Y'", :month=>"'%m'", :day=>"'%d'", :hour=>"'%H'", :minute=>"'%M'", :second=>"'%f'"}
NOT_SPACE = Dataset::NOT_SPACE
COMMA = Dataset::COMMA
PAREN_CLOSE = Dataset::PAREN_CLOSE
AS = Dataset::AS
APOS = Dataset::APOS
EXTRACT_OPEN = "CAST(strftime(".freeze
EXRACT_CLOSE = ') AS '.freeze
NUMERIC = 'NUMERIC'.freeze
INTEGER = 'INTEGER'.freeze
BACKTICK = '`'.freeze
BLOB_START = "X'".freeze
HSTAR = "H*".freeze

Public Instance methods

SQLite does not support pattern matching via regular expressions. SQLite is case insensitive (depending on pragma), so use LIKE for ILIKE.

[Source]

     # File lib/sequel/adapters/shared/sqlite.rb, line 418
418:       def complex_expression_sql_append(sql, op, args)
419:         case op
420:         when :~, '!~''!~', '~*''~*', '!~*''!~*'
421:           raise Error, "SQLite does not support pattern matching via regular expressions"
422:         when :ILIKE
423:           super(sql, :LIKE, args.map{|a| SQL::Function.new(:upper, a)})
424:         when "NOT LIKE""NOT LIKE", "NOT ILIKE""NOT ILIKE"
425:           sql << NOT_SPACE
426:           complex_expression_sql_append(sql, (op == "NOT ILIKE""NOT ILIKE" ? :ILIKE : :LIKE), args)
427:         when :^
428:           sql << complex_expression_arg_pairs(args) do |a, b|
429:             a = literal(a)
430:             b = literal(b)
431:             "((~(#{a} & #{b})) & (#{a} | #{b}))"
432:           end
433:         when :extract
434:           part = args.at(0)
435:           raise(Sequel::Error, "unsupported extract argument: #{part.inspect}") unless format = EXTRACT_MAP[part]
436:           sql << EXTRACT_OPEN << format << COMMA
437:           literal_append(sql, args.at(1))
438:           sql << EXRACT_CLOSE << (part == :second ? NUMERIC : INTEGER) << PAREN_CLOSE
439:         else
440:           super
441:         end
442:       end

MSSQL doesn‘t support the SQL standard CURRENT_DATE or CURRENT_TIME

[Source]

     # File lib/sequel/adapters/shared/sqlite.rb, line 445
445:       def constant_sql_append(sql, constant)
446:         if c = CONSTANT_MAP[constant]
447:           sql << c
448:         else
449:           super
450:         end
451:       end

SQLite performs a TRUNCATE style DELETE if no filter is specified. Since we want to always return the count of records, add a condition that is always true and then delete.

[Source]

     # File lib/sequel/adapters/shared/sqlite.rb, line 456
456:       def delete
457:         @opts[:where] ? super : filter(1=>1).delete
458:       end

Return an array of strings specifying a query explanation for a SELECT of the current dataset.

[Source]

     # File lib/sequel/adapters/shared/sqlite.rb, line 462
462:       def explain
463:         db.send(:metadata_dataset).clone(:sql=>"EXPLAIN #{select_sql}").
464:           map{|x| "#{x[:addr]}|#{x[:opcode]}|#{(1..5).map{|i| x[:"p#{i}"]}.join('|')}|#{x[:comment]}"}
465:       end

HAVING requires GROUP BY on SQLite

[Source]

     # File lib/sequel/adapters/shared/sqlite.rb, line 468
468:       def having(*cond)
469:         raise(InvalidOperation, "Can only specify a HAVING clause on a grouped dataset") unless @opts[:group]
470:         super
471:       end

SQLite uses the nonstandard ` (backtick) for quoting identifiers.

[Source]

     # File lib/sequel/adapters/shared/sqlite.rb, line 474
474:       def quoted_identifier_append(sql, c)
475:         sql << BACKTICK << c.to_s << BACKTICK
476:       end

When a qualified column is selected on SQLite and the qualifier is a subselect, the column name used is the full qualified name (including the qualifier) instead of just the column name. To get correct column names, you must use an alias.

[Source]

     # File lib/sequel/adapters/shared/sqlite.rb, line 482
482:       def select(*cols)
483:         if ((f = @opts[:from]) && f.any?{|t| t.is_a?(Dataset) || (t.is_a?(SQL::AliasedExpression) && t.expression.is_a?(Dataset))}) || ((j = @opts[:join]) && j.any?{|t| t.table.is_a?(Dataset)})
484:           super(*cols.map{|c| alias_qualified_column(c)})
485:         else
486:           super
487:         end
488:       end

SQLite does not support INTERSECT ALL or EXCEPT ALL

[Source]

     # File lib/sequel/adapters/shared/sqlite.rb, line 491
491:       def supports_intersect_except_all?
492:         false
493:       end

SQLite does not support IS TRUE

[Source]

     # File lib/sequel/adapters/shared/sqlite.rb, line 496
496:       def supports_is_true?
497:         false
498:       end

SQLite does not support multiple columns for the IN/NOT IN operators

[Source]

     # File lib/sequel/adapters/shared/sqlite.rb, line 501
501:       def supports_multiple_column_in?
502:         false
503:       end

SQLite supports timezones in literal timestamps, since it stores them as text. But using timezones in timestamps breaks SQLite datetime functions, so we allow the user to override the default per database.

[Source]

     # File lib/sequel/adapters/shared/sqlite.rb, line 508
508:       def supports_timestamp_timezones?
509:         db.use_timestamp_timezones?
510:       end

SQLite cannot use WHERE ‘t’.

[Source]

     # File lib/sequel/adapters/shared/sqlite.rb, line 513
513:       def supports_where_true?
514:         false
515:       end

[Validate]