题解 | #网易云音乐推荐(网易校招笔试真题)#

# select  distinct c.music_name 
# from follow a inner join music_likes b on a.follower_id=b.user_id inner join music c on c.id=b.music_id
# where a.user_id=1 and b.music_id not in (select music_id from music_likes where user_id=1)
# order by c.id
# 当distinct和order by 同时使用会报错,因为先执行distinct再执行order by,当我们没法对去重前的数据进行排序,可以通过子查询进行解决
select music_name from 
(select  distinct c.music_name,c.id
from follow a inner join music_likes b on a.follower_id=b.user_id inner join music c on c.id=b.music_id
where a.user_id=1 and b.music_id not in (select music_id from music_likes where user_id=1)) t
order by id