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
ROUND(AVG(rt.r),4)
FROM(
SELECT
COUNT(q2.device_id) / COUNT(q1.device_id) AS r
FROM
question_practice_detail q1
LEFT JOIN question_practice_detail q2 ON q1.device_id = q2.device_id
AND q2.date = q1.date + 1
GROUP BY
q1.device_id, q1.date
) AS rt;
