Query to delete orphan records [SOLVED]

[Psycho]

I have three table with the following pertinent fields:

[movies]
- movie_id
- movie_name

[genres]
- genre_id
- genre_name

[movie_genres]
- movie_id
- genre_id

Now, if I have a genre that is associated with only one movie and then modify the movie to no longer be associated with the genre, I want to run a query to delete the orphan genre. In other words I need to delete records from the 'genres' table where the 'genre_id' does not exist in the 'movies_genres' table. How would I create that query?

$sql = "DELETE FROM genres WHERE ????";

[shoz]

[code]
DELETE
genres
FROM
genres
LEFT JOIN
movie_genres
ON
genres.genre_id = movie_genres.genre_id
WHERE
movie_genres.genre_id IS NULL
[/code]

http://dev.mysql.com/doc/refman/5.0/en/join.html
http://dev.mysql.com/doc/refman/5.0/en/delete.html

[Psycho]

Thank you!