题解 | #牛客每个人最近的登录日期(二)#

三表连接， 最关键的是确保唯一的id和最近的登录日期

select u.name u_n, c.name c_n, l.date date
from login l
join user u
on l.user_id = u.id
join client c
on l.client_id=c.id
where (l.user_id, l.date) in
(select user_id, max(date)
from login
group by user_id)
order by u_n;