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
EXTRACT_CLOSE = ') AS '.freeze
NUMERIC = 'NUMERIC'.freeze
INTEGER = 'INTEGER'.freeze
BACKTICK = '`'.freeze
BACKTICK_RE = /`/.freeze
DOUBLE_BACKTICK = '``'.freeze
BLOB_START = "X'".freeze
HSTAR = "H*".freeze
DATE_OPEN = "date(".freeze
DATETIME_OPEN = "datetime(".freeze

Public Instance methods

[Source]

     # File lib/sequel/adapters/shared/sqlite.rb, line 434
434:       def cast_sql_append(sql, expr, type)
435:         if type == Time or type == DateTime
436:           sql << DATETIME_OPEN
437:           literal_append(sql, expr)
438:           sql << PAREN_CLOSE
439:         elsif type == Date
440:           sql << DATE_OPEN
441:           literal_append(sql, expr)
442:           sql << PAREN_CLOSE
443:         else
444:           super
445:         end
446:       end

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 451
451:       def complex_expression_sql_append(sql, op, args)
452:         case op
453:         when :~, '!~''!~', '~*''~*', '!~*''!~*'
454:           raise Error, "SQLite does not support pattern matching via regular expressions"
455:         when :ILIKE
456:           super(sql, :LIKE, args.map{|a| SQL::Function.new(:upper, a)})
457:         when "NOT LIKE""NOT LIKE", "NOT ILIKE""NOT ILIKE"
458:           sql << NOT_SPACE
459:           complex_expression_sql_append(sql, (op == "NOT ILIKE""NOT ILIKE" ? :ILIKE : :LIKE), args)
460:         when :^
461:           sql << complex_expression_arg_pairs(args) do |a, b|
462:             a = literal(a)
463:             b = literal(b)
464:             "((~(#{a} & #{b})) & (#{a} | #{b}))"
465:           end
466:         when :extract
467:           part = args.at(0)
468:           raise(Sequel::Error, "unsupported extract argument: #{part.inspect}") unless format = EXTRACT_MAP[part]
469:           sql << EXTRACT_OPEN << format << COMMA
470:           literal_append(sql, args.at(1))
471:           sql << EXTRACT_CLOSE << (part == :second ? NUMERIC : INTEGER) << PAREN_CLOSE
472:         else
473:           super
474:         end
475:       end

SQLite has CURRENT_TIMESTAMP and related constants in UTC instead of in localtime, so convert those constants to local time.

[Source]

     # File lib/sequel/adapters/shared/sqlite.rb, line 479
479:       def constant_sql_append(sql, constant)
480:         if c = CONSTANT_MAP[constant]
481:           sql << c
482:         else
483:           super
484:         end
485:       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 490
490:       def delete
491:         @opts[:where] ? super : where(1=>1).delete
492:       end

Return an array of strings specifying a query explanation for a SELECT of the current dataset. Currently, the options are ignore, but it accepts options to be compatible with other adapters.

[Source]

     # File lib/sequel/adapters/shared/sqlite.rb, line 497
497:       def explain(opts=nil)
498:         # Load the PrettyTable class, needed for explain output
499:         Sequel.extension(:_pretty_table) unless defined?(Sequel::PrettyTable)
500: 
501:         ds = db.send(:metadata_dataset).clone(:sql=>"EXPLAIN #{select_sql}")
502:         rows = ds.all
503:         Sequel::PrettyTable.string(rows, ds.columns)
504:       end

HAVING requires GROUP BY on SQLite

[Source]

     # File lib/sequel/adapters/shared/sqlite.rb, line 507
507:       def having(*cond)
508:         raise(InvalidOperation, "Can only specify a HAVING clause on a grouped dataset") unless @opts[:group]
509:         super
510:       end

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

[Source]

     # File lib/sequel/adapters/shared/sqlite.rb, line 513
513:       def quoted_identifier_append(sql, c)
514:         sql << BACKTICK << c.to_s.gsub(BACKTICK_RE, DOUBLE_BACKTICK) << BACKTICK
515:       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 521
521:       def select(*cols)
522:         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)})
523:           super(*cols.map{|c| alias_qualified_column(c)})
524:         else
525:           super
526:         end
527:       end

SQLite does not support INTERSECT ALL or EXCEPT ALL

[Source]

     # File lib/sequel/adapters/shared/sqlite.rb, line 530
530:       def supports_intersect_except_all?
531:         false
532:       end

SQLite does not support IS TRUE

[Source]

     # File lib/sequel/adapters/shared/sqlite.rb, line 535
535:       def supports_is_true?
536:         false
537:       end

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

[Source]

     # File lib/sequel/adapters/shared/sqlite.rb, line 540
540:       def supports_multiple_column_in?
541:         false
542:       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 547
547:       def supports_timestamp_timezones?
548:         db.use_timestamp_timezones?
549:       end

SQLite cannot use WHERE ‘t’.

[Source]

     # File lib/sequel/adapters/shared/sqlite.rb, line 552
552:       def supports_where_true?
553:         false
554:       end

[Validate]