题解 | #计算用户的平均次日留存率#

select count( a.device_id)/count( b.device_id)
from 
(select distinct device_id,date
from 
(select
        distinct device_id,
        date as date,
        lead(date) over (partition by device_id order by date) as date2
from question_practice_detail)k
where date=date2-1 )a
right join 
(select distinct device_id,date from question_practice_detail) b
using(device_id,date)