题解 | 推荐内容准确的用户平均评分
推荐内容准确的用户平均评分
https://www.nowcoder.com/practice/2dcac73b647247f0aef0b261ed76b47e
SELECT
ROUND(AVG(t2.score),3) AS avg_score
FROM
recommend_tb as t1 right join user_action_tb as t2 on t1.rec_user=t2.user_id AND t1.rec_info_l=t2.hobby_l
WHERE
t1.rec_user=t2.user_id;
为什么用right join不行？应该也可以去重啊
