query problems

[angelus]

Im trying to make a query (or two) to retrieve info listed in two tables. This is for an online song database i am developing. The structure of them is:

Playlist (P):
id (primary)
artist
title
genre

example data:
1, muse, plug in baby, rock
2, eminem, lose yourself, rap
3, smashing pumpkins, disarm, prog. rock

Songlist (S):
songid
hostid
genre

example data:
1, 5, rock
2, 5, hip-hop
3, 9, rock

S.songid refers to the track information on Playlist
S.hostid refers to the person who has added that particular song to their songlist.
S.genre referes to the genre they have assigned it to (which is user-definable)
S.hostid and S.songid are repeated throughout songlist, but every entry in playlist is unique

I want to pull all of the information out of playlist where a song isn't listed in their songlist
(i.e. if i added several new songs, the user coudl brose through and select the songs they want to add)

If anyone can, and is willing, to help me, then i thank you in advance.

[[deleted]]

You can probably do this using a LEFT JOIN.

A LEFT JOIN is like a normal JOIN, except that whenever there is no match in the second column, then NULLs are displayed instead.

So if you do

SELECT a., b.
FROM a LEFT JOIN b ON a.somthing=b.somethingelse
AND b.somethingelse IS NULL;

then you will get all rows where there IS data in 'a', but there is no match in 'b'