Re: Question about One to Many relationships

>> And I want to link the band to the album, but, if the album is a
>> compilation it'll be linked to multiple band.ids, so i can't just add
>> a column like:

For a compilation, you should link a band to a track, not an album. This
opens another can of worms...

I would use the following tables :

CREATE TABLE albums (
id SERIAL PRIMARY KEY
... other data
);

CREATE TABLE tracks (
id SERIAL PRIMARY KEY
album_id INTEGER NOT NULL REFERENCES albums( id )
... other data
):

CREATE TABLE artists (
id SERIAL PRIMARY KEY
... other data
);

-- A role is : composer, performer, singer, DJ, compilation maker, lead
violonist, etc.
CREATE TABLE roles (
id SERIAL PRIMARY KEY
... other data
);

CREATE TABLE track_artists (
track_id INTEGER NOT NULL REFERENCES tracks( id )
role_id INTEGER NOT NULL REFERENCES roles( id )
artist_id INTEGER NOT NULL REFERENCES artists( id )
);

And you may also with to specify main artists for an album :

CREATE TABLE track_artists (
album_id INTEGER NOT NULL REFERENCES albums( id )
role_id INTEGER NOT NULL REFERENCES roles( id )
artist_id INTEGER NOT NULL REFERENCES artists( id )
);

You will then need a few LEFT JOINs and to get the artists for a track. It
is interesting to know if the artist comes from the album or from the
track. For instance the composer of the whole album might invite a guest
singer on some tracks.