题解 | #计算用户的平均次日留存率#

with u1 as (select distinct device_id,date from question_practice_detail) select (count(u2.device_id))/(count(u1.device_id)) from u1 left join u1 as u2 on u2.date=date_add(u1.date,interval 1 day) and u1.device_id=u2.device_id