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(distinct b.device_id, b.date) / count(distinct a.device_id, a.date) as avg_ret
from
question_practice_detail a
left JOIN question_practice_detail b on a.date = b.date -1
and a.device_id = b.device_id
a 是当天的用户，b是第二天的用户
