题解 | 推荐内容准确的用户平均评分

SELECT
    ROUND(
        SUM(DISTINCT u.score) / COUNT(DISTINCT u.user_id),
        3
    ) AS avg_score
FROM
    recommend_tb as r
    JOIN user_action_tb as u ON r.rec_user = u.user_id
WHERE
    r.rec_info_l = u.hobby_l
ORDER BY
    u.user_id