如何在從子查詢返回多列時只使用一列？

Question

說我有喜歡

select deptNo, count(*) 
from employee group by deptNo 

子查詢，我想在我的主查詢只使用COUNT（*），我該怎麼辦呢？

例如：查詢如count(*) in (select deptNo, count(*) from employee group by deptNo); 或者有什麼辦法呢？

Answer 1

select avg(cnt) 
from (
    select deptNo, count(*) as cnt 
    from employee group by deptNo) src 

Answer 2

select t.count1 from 
(select deptNo,count(*) as count1 from employee group by deptNo) as t 

嘗試有一個別名爲內query.I計數假設你只需要在這裏列的count1。（我有一個名爲列的count1）