帮忙看看，如何简化这条mysql语句，并且优化查询效率～

select <br />  '' as type, <br />  `class`.`name` as cname, <br />  `score`.`cid`, <br />  `score`.`uid`, <br />  `user`.`name` as uname,<br />  `score`<br />from `score`<br />right join `class` on `score`.`cid` = `class`.`cid`<br />left join `user` on `score`.`uid` = `user`.`uid`<br /><br />union all(<br />  select <br />    '汇总', <br />    `c`.`cname`, <br />    `c`.`cid`, <br />    `c`.`uid`, <br />    count(`cid`) as uname,<br />    sum(`score`) as score<br />  from (<br />    select <br />      '' as type, <br />      `class`.`name` as cname, <br />      `score`.`cid`, <br />      `score`.`uid`, <br />      `user`.`name` as uname,<br />      `score`<br />    from `score`<br />    right join `class` on `score`.`cid` = `class`.`cid`<br />    left join `user` on `score`.`uid` = `user`.`uid`<br />  ) c group by `cname`<br />)<br /><br />order by `cname` asc, `type` asc;