高频 SQL 50 题（基础版）_550. 游戏玩法分析 IV

select IFNULL(round(count(distinct(restult.player_id))/count(distinct(Activity.player_id)),2),0) as fraction 
from(select Activity.player_id,Activity.event_datefrom Activity join(select player_id, DATE_ADD(MIN(event_date), INTERVAL 1 DAY) as second_datefrom Activitygroup by player_id)as t1 on t1.player_id = Activity.player_id and t1.second_date  = Activity.event_date
) as restult,Activity