Re: Principle of Orthogonal Design
From: Brian Selzer <brian_at_selzer-software.com>
Date: Thu, 07 Feb 2008 13:54:04 GMT
Message-ID: <04Eqj.7465$0o7.5640_at_newssvr13.news.prodigy.net>
Date: Thu, 07 Feb 2008 13:54:04 GMT
Message-ID: <04Eqj.7465$0o7.5640_at_newssvr13.news.prodigy.net>
"JOG" <jog_at_cs.nott.ac.uk> wrote in message
news:c8bd75c2-5a4b-4456-8646-4ed912cc578b_at_i29g2000prf.googlegroups.com...
> On Feb 7, 11:21 am, "Brian Selzer" <br..._at_selzer-software.com> wrote:
>> [snip]
>> A join is not a constraint, is it?
>
> Now that's a very interesting question. Let me be polemic and say I
> think it is.
Interesting indeed. So, for example, the join of relations
P {A, B, C} and
Q{D, E, F, G}
yields a relation with the heading,
{A, B, C, D, E, F, G}.
Can you explain what is constrained by P JOIN Q? Received on Thu Feb 07 2008 - 14:54:04 CET