Left outer join

eSymphony's marketing department has noticed that songs in playlists get purchased more often. Since there's a Led Zeppelin anniversary coming up, they want to know how many songs composed by Jimmy Page, the founder of the band, are not in a playlist yet.

You decide to use a left outer join to solve this problem. By doing this, you are sure all tracks, even the ones that aren't included in a playlist, are shown.