mysql分组排序后再给查询结果加序号

SELECT @id := @id + 1 AS id, task., @ranking := @ranking + 1 AS ranking FROM ( SELECT executer AS executor, count() AS assignTaskNum, sum( IF ( complete_date IS NULL, 0, 1 )) AS onScheduleNum FROM mes_jobsub_task GROUP BY executer ORDER BY onScheduleNum DESC, executer ASC ) AS task, (SELECT @id := 0 ) id, (SELECT @ranking := 0 ) ranking `