sql 有重复字段的多个表查询时，数据被覆盖怎么解决？

Posted 2023-03-27

select a.no
,sum(case when a.index = 1 then a.value else 0 end)/count(distinct a.calcdate) as aa
,sum(case when c.index = 5 then c.value else 0 end)/count(distinct c.calcdate) as cc
from A a join C c on a.bid = c.bid
group by a.no

表A和表C字段相同，都有no,index,value,calcdate，现在运行后c的值会覆盖a的值运算
求不会覆盖的方法

参考技术A select a.no
,sum(case when a.index = 1 then a.value else 0 end)/count(distinct a.calcdate) as aa
from A
group by a.no
union all
select c.no
,sum(case when c.index = 5 then c.value else 0 end)/count(distinct c.calcdate) as cc
from C
group by C.no追问

运行后没有cc那列，只有no和aa

追答

select no
,sum(case when index = 1 then value else 0 end)/count(distinct calcdate) as aa
from A
group by no
union all
select no
,sum(case when index = 5 then value else 0 end)/count(distinct calcdate) as aa
from C
group by no
这样看下数据对不对,上下查询的结果都放同一个字段里面

追问

不行的

追答

我后面这个代码运行完是怎么样的，截图看下

MySQL查询时，怎么排除某个字段查询

参考技术A select [需要的字段] from [表] where [查询条件]
需要的字段这边填入需要的字段。如果需要所有的字段则填入*