On Wed, Jul 30, 2003 at 02:35:20PM -0500, Dave Dribin wrote:
> Hi, I'm having trouble with what I think should be an easy query. For
> simplicity, I will use a CD database as an example. Each CD may have
> multiple genres. Here's some sample data:
>
> Artist Title Genres
> ---------------------- ------------------------------ ----------------
> Miles Davis Some Kind of Blue Jazz
> Metallica Ride the Lightning Rock
> Chemical Brothers Surrender Electronic
> Radiohead OK Computer Rock, Electronic
>
> For simplicities sake, let's ignore normalization on artist and genre,
> and say the tables look like:
>
> CREATE TABLE cd (
> id integer unique,
> artist varchar(25),
> title varchar(25)
> );
>
> CREATE TABLE cd_genres (
> cd_id integer,
> genre varchar(25)
> );
Assuming that each CD can have several rows in cd_genres,
SELECT id, artist, title
FROM cd
WHERE id NOT IN ( SELECT cd_id FROM cd_genres WHERE genre = 'Rock' );
will do what you want. Your co-worker is perhaps used to certain lesser
databases which don't support subselects...
Richard
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TIP 9: the planner will ignore your desire to choose an index scan if your
joining column's datatypes do not match
