题解 | #牛客每个人最近的登录日期(二)#
牛客每个人最近的登录日期(二)
http://www.nowcoder.com/practice/7cc3c814329546e89e71bb45c805c9ad
这道题我是这样写的，使用row_number对每个用户的登录日期进行排序，然后取出第一条数据就是最近一次登录~
select a1.u_n, a1.c_n, a1.date from
(select u.name as u_n
,c.name as c_n
,l.date as date
,row_number() over(partition by u.id order by date desc ) as num
from user u, client c, login l
where u.id = l.user_id and c.id = l.client_id) a1
where a1.num = 1
order by a1.u_n