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Re: Interesting article: In the Beginning: An RDBMS history

From: David Cressey <dcressey_at_verizon.net>
Date: Mon, 10 Apr 2006 16:54:06 GMT
Message-ID: <O4w_f.7994$rm3.226@trndny06>

"x" <x_at_not-exists.org> wrote in message news:e1dek1$vem$1_at_emma.aioe.org...
>
> "David Cressey" <dcressey_at_verizon.net> wrote in message
> news:ZYNZf.133$ee6.86_at_trndny01...
> >
> > "mAsterdam" <mAsterdam_at_vrijdag.org> wrote in message
> > news:4437030e$0$11073$e4fe514c_at_news.xs4all.nl...
>
> > > As soon as it does change (e.g. add/scratch an
> > > attribute/column/field/whatever horizontal thingy)
> > > the /number/ references have to be re-examined whereas the /name/
> > > simply continues to refer to the correct (as
> > > correct as it was to begin with) data.
>
> > The above is true if the numbers are determined by a position in a list.
> If
> > the numbers are simply assigned
> > sequentially, as if they were "names", you could alter relational
tables
> > or relations without regard to the
> > "column numbers". However, since attributes in a relation are written
> down
> > by POSITION, and not merely by numerical name, your point is valid
with
> > regard to mathematical relations.
>
>
> > Going back to the original question which was (roughly) "what's the
> > difference, in mathematics, between a relation and a relationship",
the
> > question you raise may not arise. I declined to offer either Codd's
> answer
> > or my own. I didn't offer Codd's because I don't know it. I didn't
offer
> > mine because I'm not a mathematician.
>
> Well, the question was more like: a relation with attribute names in Chris
> Date style is more similar to a Codd's relation, to a relationship or to
> something in between ?

Ok, this wasn't the original post, but it was a question as you asked it. Here it is, verbatim:

> What is the difference between a "name" and a "position" from a
> mathematically point of view ?
Received on Mon Apr 10 2006 - 11:54:06 CDT

Original text of this message

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