题解 | #计算次日留存率#
计算用户的平均次日留存率
http://www.nowcoder.com/practice/126083961ae0415fbde061d7ebbde453
with a as( select DISTINCT device_id,date from question_practice_detail) select count(b.date)/count(a.date) as avg_ret from a left join a b on a.device_id = b.device_id and b.date = date_add(a.date, interval 1 day) -- 创建临时表的做法
