Salve a tutti. Ho una tabella con dentro 2 dati che sono foreign key di altre 2 tabelle. Come faccio a fare la foreign key? Ma devo usare anche INDEX, cos è?
Ho fatto così:
codice:
CREATE TABLE `Vendita` ( `id_vendita` integer unsigned NOT NULL auto_increment,
`libro` integer unsigned NOT NULL,
`seller` integer unsigned NOT NULL,
`prezzo` double unsigned NOT NULL,
`commento` varchar(200),
`isbn` integer NOT NULL,
`data` date NOT NULL,
`edizione` integer,
`lingua` integer unsigned NOT NULL,
`condizione` integer unsigned NOT NULL,
`eta` integer unsigned NOT NULL,
`formato` integer unsigned NOT NULL,
`copertina` integer unsigned,
`soggetto` integer unsigned,
PRIMARY KEY (`id_vendita`),
FOREIGN KEY (libro) REFERENCES Book(id_book) ON DELETE CASCADE ON UPDATE CASCADE,
FOREIGN KEY (seller) REFERENCES Seller(id_seller) ON DELETE CASCADE ON UPDATE CASCADE,
FOREIGN KEY (lingua) REFERENCES Language(id_language) ON DELETE CASCADE ON UPDATE CASCADE,
FOREIGN KEY (condizione) REFERENCES Condition(id_condition) ON DELETE CASCADE ON UPDATE CASCADE,
FOREIGN KEY (eta) REFERENCES Age(id_age) ON DELETE CASCADE ON UPDATE CASCADE,
FOREIGN KEY (formato) REFERENCES Format(id_format) ON DELETE CASCADE ON UPDATE CASCADE,
FOREIGN KEY (copertina) REFERENCES Binding(id_binding) ON DELETE CASCADE ON UPDATE CASCADE,
FOREIGN KEY (soggetto) REFERENCES Subject(id_subject) ON DELETE CASCADE ON UPDATE CASCADE )
Mi da errore purtroppo e non so perchè...chi mi aiuta???