select date ,ifnull(round((sum(case when (user_id,date_add(date,interval 1 day))in (select user_id,date from login) and (user_id,date)in (select user_id,min(date)from login group by user_id) then 1 else 0 end))/ (sum(case when (user_id,date)in (select user_id,min(date)from login group by user_id) then 1 else 0 end)),3),0)as p from login group by date order by date; 这种更容易理解。