Re: atomic
From: Bob Badour <bbadour_at_pei.sympatico.ca>
Date: Mon, 05 Nov 2007 14:50:32 -0400
Message-ID: <472f65fe$0$14862$9a566e8b_at_news.aliant.net>
>
> Sorry, let me take that back, I think I should have said intersection,
> not cartesian product.
Date: Mon, 05 Nov 2007 14:50:32 -0400
Message-ID: <472f65fe$0$14862$9a566e8b_at_news.aliant.net>
paul c wrote:
> paul c wrote:
> ...
>
>> if those make sense, by the D&D definition of "cartesian product", I >> think r1 |x| r2 would be empty and I presume so would I(r1 |x| r2).
>
> Sorry, let me take that back, I think I should have said intersection,
> not cartesian product.
The join is empty. The intersection is empty. If one renamed one of the "car" attributes to something else, the join would have 4 rows. Received on Mon Nov 05 2007 - 19:50:32 CET