# File lib/criteria/sql.rb, line 209
    def _mkjoin(s, *args)
      return unless @join_type

      # JOIN clause
      s << " #@join_type "
      s << @joins.map { |j| j.to_s }.join(", ")

      if(@join_on.is_a? SQLCriterion)
        s << " ON "
        s << @join_on.to_s
      elsif(@join_on.is_a? Array)
        s << " USING("
        s << @join_on.join(", ")
        s << ")"
      end
    end