delete_records

# File activerecord/lib/active_record/associations/has_many_association.rb, line 53
        def delete_records(records)
          case @reflection.options[:dependent]
            when :destroy
              records.each(&:destroy)
            when :delete_all
              @reflection.klass.delete(records.map(&:id))
            else
              ids = quoted_record_ids(records)
              @reflection.klass.update_all(
                "#{@reflection.primary_key_name} = NULL", 
                "#{@reflection.primary_key_name} = #{@owner.quoted_id} AND #{@reflection.klass.primary_key} IN (#{ids})"
              )
          end
        end