题解 | #网易云音乐推荐(网易校招笔试真题)#

--用户已经喜欢的音乐 t1
SELECT music_id FROM music_likes WHERE user_id = 1;
--用户关注的人 t2
SELECT follower_id FROM follow WHERE user_id = 1;
--用户关注的人喜欢的音乐 t3
SELCT DISTINCT music_id 
FROM music_likes 
WHERE user_id = ANY(t2)
    AND music_id NOT IN (t1);

--音乐id与音乐名字结合 t4
SELCT DISTINCT m.music_name 
FROM music_likes ml , music m
WHERE ml.user_id = ANY(t2)
    AND ml.music_id NOT IN (t1)
    AND ml.music_id = m.id;