Question

I am trying to create a composite key for MYSQL, but i dont know how to, ive tried the following;

CREATE TABLE order_line(
order_id int NOT NULL AUTO_INCREMENT,
car_id int NOT NULL AUTO_INCREMENT,
PRIMARY KEY (order_id, car_id));

ALTER TABLE order_line ADD CONSTRAINT order_line_FK FOREIGN KEY (order_id) REFERENCES orders (order_id);
ALTER TABLE order_line ADD CONSTRAINT order_line_FK2 FOREIGN KEY (car_id) REFERENCES car (car_id);

Answer 1

Okay, i was able to do it like;

CREATE TABLE order_line (
order_id int NOT NULL,
car_id int NOT NULL);

ALTER TABLE order_line ADD CONSTRAINT order_line_PK PRIMARY KEY (order_id, car_id);
ALTER TABLE order_line ADD CONSTRAINT order_line_FK FOREIGN KEY (order_id) REFERENCES orders (order_id);
ALTER TABLE order_line ADD CONSTRAINT order_line_FK2 FOREIGN KEY (car_id) REFERENCES car (car_id);