Module | Sequel::SQLite::DatasetMethods |
In: |
lib/sequel/adapters/shared/sqlite.rb
|
Instance methods for datasets that connect to an SQLite database
CONSTANT_MAP | = | {:CURRENT_DATE=>"date(CURRENT_TIMESTAMP, 'localtime')".freeze, :CURRENT_TIMESTAMP=>"datetime(CURRENT_TIMESTAMP, 'localtime')".freeze, :CURRENT_TIME=>"time(CURRENT_TIMESTAMP, 'localtime')".freeze} |
EMULATED_FUNCTION_MAP | = | {:char_length=>'length'.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 |
ONLY_OFFSET | = | " LIMIT -1 OFFSET ".freeze |
OR | = | " OR ".freeze |
SELECT_VALUES | = | "VALUES ".freeze |
# File lib/sequel/adapters/shared/sqlite.rb, line 543 543: def cast_sql_append(sql, expr, type) 544: if type == Time or type == DateTime 545: sql << DATETIME_OPEN 546: literal_append(sql, expr) 547: sql << PAREN_CLOSE 548: elsif type == Date 549: sql << DATE_OPEN 550: literal_append(sql, expr) 551: sql << PAREN_CLOSE 552: else 553: super 554: end 555: end
SQLite doesn‘t support a NOT LIKE b, you need to use NOT (a LIKE b). It doesn‘t support xor or the extract function natively, so those have to be emulated.
# File lib/sequel/adapters/shared/sqlite.rb, line 559 559: def complex_expression_sql_append(sql, op, args) 560: case op 561: when "NOT LIKE""NOT LIKE", "NOT ILIKE""NOT ILIKE" 562: sql << NOT_SPACE 563: complex_expression_sql_append(sql, (op == "NOT ILIKE""NOT ILIKE" ? :ILIKE : :LIKE), args) 564: when :^ 565: complex_expression_arg_pairs_append(sql, args){|a, b| Sequel.lit(["((~(", " & ", ")) & (", " | ", "))"], a, b, a, b)} 566: when :** 567: unless (exp = args[1]).is_a?(Integer) 568: raise(Sequel::Error, "can only emulate exponentiation on SQLite if exponent is an integer, given #{exp.inspect}") 569: end 570: case exp 571: when 0 572: sql << '1' 573: else 574: sql << '(' 575: arg = args.at(0) 576: if exp < 0 577: invert = true 578: exp = exp.abs 579: sql << '(1.0 / (' 580: end 581: (exp - 1).times do 582: literal_append(sql, arg) 583: sql << " * " 584: end 585: literal_append(sql, arg) 586: sql << PAREN_CLOSE 587: if invert 588: sql << "))" 589: end 590: end 591: when :extract 592: part = args.at(0) 593: raise(Sequel::Error, "unsupported extract argument: #{part.inspect}") unless format = EXTRACT_MAP[part] 594: sql << EXTRACT_OPEN << format << COMMA 595: literal_append(sql, args.at(1)) 596: sql << EXTRACT_CLOSE << (part == :second ? NUMERIC : INTEGER) << PAREN_CLOSE 597: else 598: super 599: end 600: end
SQLite has CURRENT_TIMESTAMP and related constants in UTC instead of in localtime, so convert those constants to local time.
# File lib/sequel/adapters/shared/sqlite.rb, line 604 604: def constant_sql_append(sql, constant) 605: if c = CONSTANT_MAP[constant] 606: sql << c 607: else 608: super 609: end 610: 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.
# File lib/sequel/adapters/shared/sqlite.rb, line 622 622: def explain(opts=nil) 623: # Load the PrettyTable class, needed for explain output 624: Sequel.extension(:_pretty_table) unless defined?(Sequel::PrettyTable) 625: 626: ds = db.send(:metadata_dataset).clone(:sql=>"EXPLAIN #{select_sql}") 627: rows = ds.all 628: Sequel::PrettyTable.string(rows, ds.columns) 629: end
Handle uniqueness violations when inserting, by using a specified resolution algorithm. With no options, uses INSERT OR REPLACE. SQLite supports the following conflict resolution algoriths: ROLLBACK, ABORT, FAIL, IGNORE and REPLACE.
Examples:
DB[:table].insert_conflict.insert(:a=>1, :b=>2) # INSERT OR IGNORE INTO TABLE (a, b) VALUES (1, 2) DB[:table].insert_conflict(:replace).insert(:a=>1, :b=>2) # INSERT OR REPLACE INTO TABLE (a, b) VALUES (1, 2)
# File lib/sequel/adapters/shared/sqlite.rb, line 666 666: def insert_conflict(resolution = :ignore) 667: clone(:insert_conflict => resolution) 668: end
Ignore uniqueness/exclusion violations when inserting, using INSERT OR IGNORE. Exists mostly for compatibility to MySQL‘s insert_ignore. Example:
DB[:table].insert_ignore.insert(:a=>1, :b=>2) # INSERT OR IGNORE INTO TABLE (a, b) VALUES (1, 2)
# File lib/sequel/adapters/shared/sqlite.rb, line 675 675: def insert_ignore 676: insert_conflict(:ignore) 677: 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.
# File lib/sequel/adapters/shared/sqlite.rb, line 646 646: def select(*cols) 647: 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)}) 648: super(*cols.map{|c| alias_qualified_column(c)}) 649: else 650: super 651: end 652: 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.
# File lib/sequel/adapters/shared/sqlite.rb, line 707 707: def supports_timestamp_timezones? 708: db.use_timestamp_timezones? 709: end