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;
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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