Re: RM VERY STRONG SUGGESTION 4: TRANSITION CONSTRAINTS
Date: Wed, 8 Sep 2010 19:41:58 -0700 (PDT)
On Sep 7, 8:23 pm, paul c <toledobythe..._at_oohay.ac> wrote:
> On 07/09/2010 3:14 PM, Reinier Post wrote:
> > Brian Seltzer wrote:
> > [...]
> >> There is a mapping from every tuple in a database to something in the
> >> microworld that is being modeled, but more importantly, every tuple
> >> maps to something that has a location in time if not also space.
> > Where exctly is 'there'?
> That doesn't matter. There is no useful mapping unless it is recorded.
> Eg., there is not 'time' in a db unless it is recorded. Brian S has a
> mental block about this. (For the sake of newcomers, this needs to be
> repeated once in a while. We all have various mental blocks, but most
> of us stop harping about them after a while.)
When I'm wrong, I admit that I'm wrong. I don't think I'm wrong, and nobody has offerred an irrefutable argument that proves me wrong; therefore, I have to conclude that I'm right.
As Codd has written, and as Bob Badour continually asserts every time the subject of surrogate keys comes up: Every key is a surrogate. A surrogate for what? For an object in the microworld being modeled. Every tuple has a superkey consisting of all prime components; every key is a surrogate; therefore every tuple has a surrogate. A surrogate for what? For an object in the microworld being modeled. If that doesn't constitute a mapping, then perhaps you can enlighten me as to what does. Received on Wed Sep 08 2010 - 21:41:58 CDT