Re: atomic
From: paul c <toledobythesea_at_ooyah.ac>
Date: Tue, 06 Nov 2007 02:29:16 GMT
Message-ID: <0kQXi.178598$Da.38157_at_pd7urf1no>
>
> The join is empty. The intersection is empty. If one renamed one of the
> "car" attributes to something else, the join would have 4 rows.
Date: Tue, 06 Nov 2007 02:29:16 GMT
Message-ID: <0kQXi.178598$Da.38157_at_pd7urf1no>
Bob Badour wrote:
> 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.
I think it would have 20! Received on Tue Nov 06 2007 - 03:29:16 CET