Hvordan opnår man det samme resultat ved hjælp af Mysql Joins i stedet for indlejrede underforespørgsler?

Du kan ændre din forespørgsel som,

For alle sange i databasen undtagen dem på din afspilningsliste

$sql1 = "Select distinct title, artist, album 
from songs where id not in(Select distinct song.id
from songs song inner join playlist playlist 
on playlist.song_id=song.id
inner join playlists playlists 
on playlists.playlist_id=playlist.playlist_id
and playlists.name = '$playlist_name')";

Dem på din afspilningsliste,

$sql2 = "Select distinct song.title, song.artist, song.album
from songs song inner join playlist playlist 
on playlist.song_id=song.id
inner join playlists playlists 
on playlists.playlist_id=playlist.playlist_id
and playlists.name = '$playlist_name'";