Question

怎么实现两个列名不一样的表嵌套查询？比如 select * from table1 where a=(select top 1 b from table2)

比如
select * from table1 where a=(select top 1 b from table2)
这样应该是不行的吧？

Answer 1

select * from table1 where a in (select top 1 b from table2) 比较慢
select * from table1 join table2 on table1.a = table2.b 比较快

Answer 2

select * from table1 where a in (select top 1 b from table2)

Answer 3

select * from table1 where a.id in(select b.id from table2)