Re: does a table always need a PK?

Leandro Guimarães Faria Corsetti Dutra <lgcdutra_at_terra.com.br> wrote in message news:<pan.2003.08.26.15.14.06.524358_at_terra.com.br>...
> Em Mon, 25 Aug 2003 04:55:02 +0000, Heikki Tuuri escreveu:
>
> > we discussed the 'correct' definition of 'relational' in
> > comp.databases.theory with several people. I think the concept is vague. For
> > example, Codd's 12 principles are not formulated as mathematical axioms.
>
> No, but some of them have clear mathematical implications --
> for example, SQL can't be relational 'cause its tables aren't relations
> but bags -- while some others are more related to good design.
>
> In any way, Codd's work is somewhat obsolete. I'd look to D&D's _TTM_.

I think I found D&D's _TTM_

http://www.acm.org/sigmod/record/issues/9503/manifesto.ps

The Third Manifesto
Hugh Darwen and C.J. Date

The article has some interesting observations on SQL as a relational database Model language.

Correct me please!

Yours Sincerely

Morten Gulbrandsen Received on Mon Sep 01 2003 - 07:54:50 CDT