题解 | 每天登陆最早的用户的内容喜好

SELECT DATE(log_time) AS log_day, l.user_id,u.hobby
FROM login_tb AS l JOIN user_action_tb AS u ON u.user_id=l.user_id
WHERE log_time IN (
SELECT MIN(TIMESTAMP(log_time)) AS min_timestamp
FROM login_tb AS l
GROUP BY DATE(log_time)
)
ORDER BY  log_day