题目描述

易错点

雇佣最多的项目可能不止有一个，可能会存在相同雇员数量的项目；
容易写成如下错误代码：

select 
project_id
from Project
group by project_id
order by count(1) desc
limit 1;

参考答案一

select 
project_id
from Project
group by project_id
having count(*) = (select count(1) from Project group by project_id order by count(1) desc limit 1)

参考答案二

select
t.project_id
from 
(select *,dense_rank()over(order by count(employee_id) desc) as m from project group by project_id) as t
where
t.m=1