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(q2.device_id) / COUNT(q1.device_id) AS avg_ret
FROM
(SELECT DISTINCT device_id, date FROM question_practice_detail)as q1
LEFT JOIN
(SELECT DISTINCT device_id, date FROM question_practice_detail) AS q2
ON q1.device_id = q2.device_id AND datediff(q2.date, q1.date) = 1
