I don't think anyone would ever say they want "id, id, id"? They would say they want "customer_id, order_id, item_id" or some such. You would then probably say, "we just use 'id' for the id of every item..." but many places that I've worked actually explicitly didn't do that for essentially this reason. Natural joins on "foo_id" "just work" if you don't give every table the same "id" column.