CREATE TABLE cds(
id serial PRIMARY KEY  -- implicit primary key constraint,
title    text NOT NULL
);

CREATE TABLE artists(
id  serial PRIMARY KEY,
name     text NOT NULL
);

CREATE TABLE cds_and_artists(
cds_id    integer REFERENCES cds (id) ON UPDATE CASCADE ON DELETE CASCADE,
artists_id integer REFERENCES artisys (id) ON UPDATE CASCADE,
CONSTRAINT cds_and_artists_pkey PRIMARY KEY (cds_id, artists_id) 
);