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
分子分母都要distinct
SELECT round(count(distinct case when diff=1 then user_id else null end)/count(distinct user_id),3)
from(
SELECT t1.user_id,(t1.date-t2.date) as diff
from login t1 left join login t2 using(user_id))a