题解 | #牛客每个人最近的登录日期(二)#
牛客每个人最近的登录日期(四)
http://www.nowcoder.com/practice/e524dc7450234395aa21c75303a42b0a
SELECT l.date,SUM(CASE WHEN l.date=s.md THEN 1 ELSE 0 END)
FROM login l LEFT JOIN (SELECT user_id,MIN(date) AS md FROM login GROUP BY user_id) AS s
ON l.user_id=s.user_id
GROUP BY l.date
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