题解 | 牛客每个人最近的登录日期(二)

方法一：
select u_n,c_n,date from 
(select u.name u_n,c.name c_n,date,row_number()over(partition by l.user_id order by date desc)  rk from login l 
inner join user u on u.id = l.user_id
inner join client c on c.id = l.client_id) e
where e.rk=1
order by u_n
注意用排名里的row_number()
方法二：
select u.name u_n,c.name c_n,l.date from login l
inner join user u on u.id = l.user_id
inner join client c on c.id = l.client_id
where (l.user_id,l.date) in 
(select user_id,max(date) date from login group by user_id)
order by u.name