题解 | #牛客每个人最近的登录日期(四)#
牛客每个人最近的登录日期(四)
http://www.nowcoder.com/practice/e524dc7450234395aa21c75303a42b0a
查出每个用户登录的最小日期,跟原表连接
select date,sum(login.date=t.min_date) from login
join
(select user_id,min(date) min_date from login group by user_id) t
on login.user_id=t.user_id
group by date order by date;