题解 | 每天登陆最早的用户的内容喜好

SELECT
    DATE(ltr.log_time) AS log_day,
    ltr.user_id,
    u.hobby
FROM
    (
        SELECT
            log_time,
            user_id,
            DENSE_RANK() OVER (PARTITION BY DATE(log_time) ORDER BY log_time) AS rk
        FROM
            login_tb
    ) AS ltr
    INNER JOIN
    user_action_tb AS u ON ltr.user_id=u.user_id
WHERE
    rk=1