not in 方法
select distinct music_name
from follow f,music_likes ml,music m
where f.follower_id=ml.user_id
and ml.music_id=m.id
and f.user_id=1
and music_name not in (
select music_name from music_likes,music
where user_id=1 and music_id=id
)
order by m.id;
not exists
select distinct m.music_name
from follow f,music_likes ml,music m
where f.follower_id=ml.user_id
and ml.music_id=m.id
and f.user_id=1
and not EXISTS
(
select * from music_likes ml,music m2
where m2.id=m.id
and ml.music_id=m2.id
and ml.user_id=1
)
order by m.id