add_group!

# File activerecord/lib/active_record/base.rb, line 1408
        def add_group!(sql, group, scope = :auto)
          if group
            sql << " GROUP BY #{group}"
          else
            scope = scope(:find) if :auto == scope
            if scope && (scoped_group = scope[:group])
              sql << " GROUP BY #{scoped_group}"
            end
          end
        end