sum()函数 我需要在sum(中进行查询)

[fangfangok]

select cl_class, sum(select num from 某表 where 某表.id=主表.id) as total from 主表 group by cl_class



我需要在sum()中进行查询，但是sum函数不允许里面再有sum或进行查询。求大家帮助.

[yangqidong]

select cl_class,
(select sum(num) from 某表 where 某表.id=主表.id) as total
from 主表 group by cl_class

[yangqidong]

select cl_class,
(select sum(num) from 某表 where 某表.id=主表.id) as total
from 主表

[yangqidong]

不需要 group by cl_class

[云想慕尘]

还可以用循环代替

[lupanlupan]

select a.cl_class,sum(b.num)
（select num from 某表 where 某表.id=主表.id）a,
主表 b
where a.id = b.id
group by a.cl_class

[lupanlupan]

上面错了

select b.cl_class,sum(a.num)
（select 主表.id,num from 某表 where 某表.id=主表.id）a,
主表 b
where a.id = b.id
group by b.cl_class

[wxg22526451]

select cl_class, (select sum(num) from 某表 where 某表.id=a.id) as total 
from 主表 a 

--或用连接
select a.cl_class, sum(b.num) as total from 主表 a join 某表 b
on 某表.id=主表.id
group by a.cl_class 

[悔说话的哑巴]

这个可以满足你的要求
select a.cl_class,sum(b.num)
（select num from 某表 where 某表.id=主表.id）a,
主表 b
where a.id = b.id
group by a.cl_class

[bw555]

直接两表做关联不可以么？用子查询的速度比关联查询速度要慢

select 主表.cl_class, 
sum(某表.num) as total 
from 主表,某表
where 某表.id=主表.id
group by cl_class 

[ws_hgo]

等下

[sdluhaibing]

楼上正解

[ws_hgo]

此贴要先聚合然后在连接

select cl_class,(select num from 
(
 select id,sum(num) num from 某表
) M join 主表 m on m.id=Z.id
) total from 主表

[ws_hgo]

也可以这样

select Z.cl_class, sum(M.num) as total from 主表 Z join 某表 M
on Z.id=M.id
group by Z.cl_class 

[ws_hgo]

[Quote=引用楼主 fangfangok 的帖子:]
select cl_class, sum(select num from 某表 where 某表.id=主表.id) as total from 主表 group by cl_class


我需要在sum()中进行查询，但是sum函数不允许里面再有sum或进行查询。求大家帮助.
[/Quote]
建议LZ对这种问题
先连接后聚合

[ndsc_cherry]

顶上

[Adechen]

select Z.cl_class, sum(M.num) as total from 主表 Z join 某表 M
on Z.id=M.id