题解 | #牛客每个人最近的登录日期(三)#
牛客每个人最近的登录日期(三)
http://www.nowcoder.com/practice/16d41af206cd4066a06a3a0aa585ad3d
select round(count(t2.user_id)/count(t1.user_id),3) as p from login t1 left join login t2 on t1.user_id=t2.user_id and t1.date=t2.date-1 where (t1.user_id, t1.date) in (select user_id, min(date) from login group by user_id)