题解 | #牛客每个人最近的登录日期(三)#

select x.date,ifnull(y.p,0) from(select distinct date from login) x left join (select a.date,round(sum(case when b.user_id is not null then 1 else 0 end)/count(*),3) p from login a left join login b on a.user_id=b.user_id and b.date=DATE_ADD(a.date,INTERVAL 1 DAY) where (a.user_id,a.date)= (select user_id,min(date) from login where user_id=a.user_id group by user_id)
group by a.date) y on x.date=y.date