题解 | #获得积分最多的人(三)#
牛客每个人最近的登录日期(三)
http://www.nowcoder.com/practice/16d41af206cd4066a06a3a0aa585ad3d
select round(count(distinct case when datediff(b.date, a.date) = 1
then a.user_id end)
/ count(distinct a.user_id),3) p
from login a join login b
on a.user_id = b.user_id;