# File lib/arel/nodes/select_core.rb, line 7
      def initialize
        @source         = JoinSource.new nil
        @top            = nil

        # http://savage.net.au/SQL/sql-92.bnf.html#set%20quantifier
        @set_quantifier = nil
        @projections    = []
        @wheres         = []
        @groups         = []
        @having         = nil
      end