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帮忙看看,如何简化这条mysql语句,并且优化查询效率~

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2016-06-13 11:43:17799browse

帮忙看看,怎么简化这条mysql语句,并且优化查询效率~~~~~

本帖最后由 setoy 于 2013-12-19 12:03:34 编辑 有三张表:管理员表,部门表,和管理员对部门的打分表,如下:


现在要对每个部门的得分情况进行查询并统计,即使某个部门没有得分纪录也要显示他的得分(0分),查询统计的结果如下所示:


mysql语句一直一知半解,东拼西凑写了一段:
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;


貌似这个sql语句太复杂了!能不能简化这条语句呢?另外从查询效率上能不能优化?
表结构、数据和代码都在这里:http://sqlfiddle.com/#!2/6f5db6/10
请帮忙看看
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