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(date2) / count(date1) as avg_ret
from (
select distinct a.device_id,
a.date date1,
b.date date2
from question_practice_detail a
left join(
select distinct device_id
,date
from question_practice_detail
) b
on a.device_id=b.device_id
and date_add(a.date, interval 1 day)=b.date
) c
