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

Instance methods for datasets that connect to an SQLite database

### Methods

cast_sql_append complex_expression_sql_append constant_sql_append delete explain having quoted_identifier_append select supports_intersect_except_all? supports_is_true? supports_multiple_column_in? supports_timestamp_timezones? supports_where_true?

### 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

cast_sql_append(sql, expr, type)

[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

complex_expression_sql_append(sql, op, args)

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

constant_sql_append(sql, constant)

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

delete()

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

explain(opts=nil)

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(*cond)

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

quoted_identifier_append(sql, c)

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

select(*cols)

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

supports_intersect_except_all?()

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

supports_is_true?()

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

supports_multiple_column_in?()

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

supports_timestamp_timezones?()

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

supports_where_true?()

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]