题解 | 网易云音乐推荐(网易校招笔试真题)

 #以下代码找出了用户id为1 的用户喜欢的音乐名，一会儿再找出他关注的人喜欢的音乐，去掉这个音乐后进行推荐
select music_name
from(
select
     distinct music_name,music_id
from
    music_likes as m_l
    left join music as m on m_l.music_id = m.id
where
    user_id in 
    (
        select
            follower_id
        from
            follow
        where
            user_id = 1
    )
    and music_id not in(
        select
            music_id
        from
            music_likes as m_l
            left join music as m on m_l.music_id = m.id
        where
            user_id = 1
    ) ) t
    order by t.music_id