union函数是否可以限定条件

Question

我现在有三个表，表1：id，money，表2：id，name，表三：id，name
现在我想要结果集表1id，money，并且还要关联上name， 但是，表2和表3中name都不全，所以需要查询两次，所以需要用到union关联两个查询，

```
select a.id,a.money ,b.name as name from 表1 a left join 表2 b on a.id=b.id
union
select a.id,a.money,c.name as name from 表1 a left join 表3 c on a.id=c.id

```select a.id,a.money ,b.name as name from 表1 a left join 表2 b on a.id=b.id
union
select a.id,a.money,c.name as name from 表1 a left join 表3 c on a.id=c.id

Answer 1

可以的

select * from(
select a.id,a.money ,b.name as name from 表1 a left join 表2 b on a.id=b.id
union
select a.id,a.money,c.name as name from 表1 a left join 表3 c on a.id=c.id
) t
where 限定条件