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 count(t2.date)/count(t1.date) from
(select distinct device_id,date from question_practice_detail) t1
left join
(select distinct device_id,date from question_practice_detail) t2
on t1.device_id = t2.device_id
and t2.date = date_add(t1.date,interval 1 day)
