题解 | #网易云音乐推荐(网易校招笔试真题)#

#follow表：user_id, follower_id
#music_likes表：user_id, music_id
#music表： id, music_name

#首先返回用户1关注的人
select follower_id from follow where user_id = 1; 
#然后看用户1的人喜欢哪些歌，并排除在外
select music_id from music_likes where user_id = 1;
#其次找出所关注人喜欢的歌并排除user_id所喜欢的歌
select music_id from music_likes 
where user_id 
in(select follower_id from follow where user_id = 1) 
and music_id not in(select music_id from music_likes where user_id = 1);


#最后的结果代码
select distinct m.music_name
from music m
join (select music_id from music_likes 
where user_id 
in(select follower_id from follow where user_id = 1) 
and music_id not in(select music_id from music_likes where user_id = 1)) t
ON m.id = t.music_id
order by id;

可能写得很乱很杂，日后再联系的时候再来改进