题解 | #计算用户的平均次日留存率#
计算用户的平均次日留存率
https://www.nowcoder.com/practice/126083961ae0415fbde061d7ebbde453
select sum(back)/count(*) as avg_ret from (select p1.device_id,p1.date,case when sum(case when datediff(p1.date,p2.date)=1 then 1 else 0 end)!=0 then 1 else 0 end as back from question_practice_detail p1 left join question_practice_detail p2 on p1.device_id=p2.device_id group by p1.device_id,p1.date) p3
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