mysql - 在 MySQL where 子句中使用生成的列

Question

如果我有一个查询，例如:

select column1, (
    select count(*) from table2
) as some_count
from table1
where column1 = 'foo'

我可以在 where 子句中使用 column1，但是如果我尝试添加

and some_count > 0

然后我收到一个错误，提示 some_count 不存在。我如何在 where 子句中使用它？

Answer 1

使用HAVING

select column1, (
    select count(*) from table2
) as some_count
from table1
HAVING some_count > 0