Re: what are keys and surrogates?
Date: Tue, 29 Jan 2008 22:09:44 -0800 (PST)
On Jan 30, 12:14 pm, Keith H Duggar <dug..._at_alum.mit.edu> wrote:
> David BL wrote:
> > Bob Badour wrote:
> > > I repeat: Why do you think representations are limited
> > > to representing to users?
> > It seems Badour assumed "possible representations" meant
> > physical and logical representations whereas Jan assumed
> > it was only logical representations.
> I am quite certain that Badour assumed that in this thread
> "possible representation" mean exactly Date's concept from
> for example Tutorial D of POSSREP. The problem is that you
> utterly ignorant of the POSSREP concept.
> Do you know who C. J. Date is? Have you studied any of his
> work? Have you even heard of Tutorial D? Why don't you run
> away somewhere, learn what a POSSREP is, come back, reread
> your posts, and realize how ignorant they are.
I have read Date's "An Introduction to Database Systems", which discusses POSSREPs.
On the contrary you have it round the wrong way. I was thinking of the set of "possible (logical) representations" as what Date would call the set of POSSREPs that have been declared to the DBMS, whereas Badour went to the trouble to draw a distinction when he stated:
Hell no! The possible representations are all possible regardless of declaration to the dbms. What the possrep concept does is provide a way to declare some subset of them to the dmbs.
[snip] Received on Wed Jan 30 2008 - 07:09:44 CET