题解 | 网易云音乐推荐(网易校招笔试真题)

select b.music_name
from 
(select distinct a.music_name, a.music_id
    from 
       (select ml.user_id, ml.music_id, m.music_name 
          from music_likes ml left join music m on ml.music_id=m.id
          where ml.user_id in (select follower_id from follow where user_id=1) and ml.music_id not in(select music_id from music_likes where user_id=1)
       ) a #a表为用户为1的关注人喜欢的音乐表，包含被关注人的id、音乐id以及音乐名
 order by a.music_id asc
 ) b #b表：因为结果不能重复，并且按music的id升序排列，所以再一次筛选