Re: Question on Structuring Product Attributes

Jan

> On Wednesday, 2 October 2013 15:59:34 UTC+10, Jan Hidders wrote:
>
> > Derek Asirvadem <derek.asirvadem_at_gmail.com> wrote:
> >
> > This one should not pass unnoticed.
> >
> > > On Monday, 18 February 2013 09:09:15 UTC+11, Eric wrote:
> > > > To quote from Codd[1970]:
> > > > "A firstorder predicate calculus suffices
> > > if the collection of relations is in normal form."
> >
> > Codd specifies what that Normal Form is, that reference is not merely a
> > generic or general term.
>
> Indeed. Also note that Codd's claim is not unproblematic. Even if you
> restrict yourself to the flat relational model, first order logic cannot
> express many practical queries.

I don't know what you mean by "*flat* relational model".

In the Relational Model, Codd specifies a specific Normalisation: a non-mathematical definition plus a method. Now that is a genuine Normalisation, completely unrelated to the abnormal "normal forms" marketed by the insane. Perhaps we could name it Codd's Normal Form or Relational Normal Form, but I think we have to stay away from any mention of "normal form" because that term and what that is, is strongly established, and we do not want to draw any relation to that. Those disgusting "normal forms" are defined in mathematical terms only, and do not provide any method.

I do not spend much time wrangling relational calculus or relational algebra, I just observe its requirements. To the best of my knowledge, first order predicate calculus has always sufficed for me.

But then all my dbs are 100% pure Relational Model (plus faithful extensions, but let's not get side-tracked), zero percent subversion. If you are influenced by the "books" re the RM, written by persons other than Dr E F Codd, then you may well have convoluted thinking, and require somewhat more than first order predicates. Maybe even Deferred Constraints Checking and similar madness.

> So what exactly does he mean by "sufficient" here?

I can't answer for you.

It is sufficient for me.

Cheers
Derek Received on Tue Feb 25 2014 - 11:01:38 CET