Instance methods for datasets that connect to an SQLite database
SQLite does not support pattern matching via regular expressions. SQLite is case insensitive (depending on pragma), so use LIKE for ILIKE.
# File lib/sequel/adapters/shared/sqlite.rb, line 435 def complex_expression_sql_append(sql, op, args) case op when :~, :'!~', :'~*', :'!~*' raise Error, "SQLite does not support pattern matching via regular expressions" when :ILIKE super(sql, :LIKE, args.map{|a| SQL::Function.new(:upper, a)}) when :"NOT LIKE", :"NOT ILIKE" sql << NOT_SPACE complex_expression_sql_append(sql, (op == :"NOT ILIKE" ? :ILIKE : :LIKE), args) when :^ sql << complex_expression_arg_pairs(args) do |a, b| a = literal(a) b = literal(b) "((~(#{a} & #{b})) & (#{a} | #{b}))" end when :extract part = args.at(0) raise(Sequel::Error, "unsupported extract argument: #{part.inspect}") unless format = EXTRACT_MAP[part] sql << EXTRACT_OPEN << format << COMMA literal_append(sql, args.at(1)) sql << EXTRACT_CLOSE << (part == :second ? NUMERIC : INTEGER) << PAREN_CLOSE else super end 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 463 def constant_sql_append(sql, constant) if c = CONSTANT_MAP[constant] sql << c else super end 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.
# File lib/sequel/adapters/shared/sqlite.rb, line 474 def delete @opts[:where] ? super : where(1=>1).delete 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 481 def explain(opts=nil) # Load the PrettyTable class, needed for explain output Sequel.extension(:_pretty_table) unless defined?(Sequel::PrettyTable) ds = db.send(:metadata_dataset).clone(:sql=>"EXPLAIN #{select_sql}") rows = ds.all Sequel::PrettyTable.string(rows, ds.columns) end
HAVING requires GROUP BY on SQLite
# File lib/sequel/adapters/shared/sqlite.rb, line 491 def having(*cond) raise(InvalidOperation, "Can only specify a HAVING clause on a grouped dataset") unless @opts[:group] super end
SQLite uses the nonstandard ` (backtick) for quoting identifiers.
# File lib/sequel/adapters/shared/sqlite.rb, line 497 def quoted_identifier_append(sql, c) sql << BACKTICK << c.to_s.gsub(BACKTICK_RE, DOUBLE_BACKTICK) << BACKTICK 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 505 def select(*cols) 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)}) super(*cols.map{|c| alias_qualified_column(c)}) else super end end
SQLite does not support INTERSECT ALL or EXCEPT ALL
# File lib/sequel/adapters/shared/sqlite.rb, line 514 def supports_intersect_except_all? false end
SQLite does not support IS TRUE
# File lib/sequel/adapters/shared/sqlite.rb, line 519 def supports_is_true? false end
SQLite does not support multiple columns for the IN/NOT IN operators
# File lib/sequel/adapters/shared/sqlite.rb, line 524 def supports_multiple_column_in? false 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 531 def supports_timestamp_timezones? db.use_timestamp_timezones? end
SQLite cannot use WHERE 't'.
# File lib/sequel/adapters/shared/sqlite.rb, line 536 def supports_where_true? false end