题解 | #牛客每个人最近的登录日期(三)#
牛客每个人最近的登录日期(三)
http://www.nowcoder.com/practice/16d41af206cd4066a06a3a0aa585ad3d
SQLite代码：
SELECT ROUND(COUNT(DISTINCT(a.user_id)) *1.0 / COUNT(DISTINCT(c.user_id)),3)
FROM login AS a,login AS c
WHERE EXISTS(
SELECT *
FROM login AS b
WHERE a.user_id=b.user_id AND DATE(a.date, '+1 day')=b.date
)
MYSQL代码：
SELECT ROUND(COUNT(DISTINCT(a.user_id)) *1.0 / COUNT(DISTINCT(c.user_id)),3)
FROM login AS a,login AS c
WHERE EXISTS(
SELECT *
FROM login AS b
WHERE a.user_id=b.user_id AND DATE_ADD(a.date,INTERVAL 1 DAY)=b.date
)
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