Re: One Ring to Bind Them

"Anthony W. Youngman" <wol_at_thewolery.demon.co.uk> wrote in message news:S3QqgiMOhy7AFwjl_at_thewolery.demon.co.uk...
> >
> >Why do you say "shouldn't?" It seems pretty clear to me that a
> >declarative approach is always better than a procedural one. (Dawn?
> >Care to rebut?)
>
> What seems clear to me is not clear to you, and vice versa.

I notice you didn't answer my question.

> >If not container/contents, what terminology would you use?
> >
> To me, an invoice is a container, and line items are contents thereof.
> You can't have the latter without the former.
>
> A company does NOT contain its invoices ...

Okay. What does contain the invoices? Or are they a top-level concept? If so, how are they related to companies?

> - a company can go bust but the
> invoices are still outstanding ...

Their financial situation is irrelevant. Perhaps you are confusing the company and the record of the company in the dbms.

> okay - we now get into all sorts of
> semantics such as "does a company entry in a database represent a real
> company, or just a fictional representation thereof?".

This is a simple question with a simple answer. The company entry in the database represents a real-world company. It is not an actual company, nor is it a representation of a representation of a company.

> But I view those two relationships as being fundamentally different, and
> they are modelled completely differently in MV. I don't think relational
> can see any difference between them.

Okay, so *how* are they different?

> >What does "declare it an index" mean? Is it like a pointer or foreign key?
> >
> Surely you declare indices in relational dbs? Same thing here.

MV terminology is quite foreign to me, so I do not assume that when an MV person uses a word I'm used to, they are using it in the same way. Note when I say foreign, I just mean that I'm not familiar with it; I don't have any opinion on the goodness or badness of the terminology. (Well, I might think "file" is an unfortunately-overloaded term.)

> So's I
> can say "SELECT CARS WITH OWNER EQ 'X'", and it doesn't need to search
> the entire CARS file, but just goes to the index and grabs a list of
> primary keys into the CARS file from the index.

Okay.

> >> Relational fits theory fine. MV fits the real world fine.
> >
> >That statement just seems totally bogus to me. Does subtraction
> >fit the real world? What happens when I subtract 5 lemons
> >from 3 lemons? Do I get -2 lemons? Can you send me a picture
> >of -2 lemons via email; I want to see what they look like.
> >
> Relational is complete, correct, and self-consistent. It's fine as a
> pure-maths theory.
>
> MV just seems to *fit* the real world rather better :-)

The simplest explanation here is that it's what you're used to, and hence it seems to fit best for you. You haven't given any evidence that it actually does fit the real world any better. Note that I consider that question unanswerable and hence irrelevant.

Marshall Received on Sat Jul 10 2004 - 04:25:01 CEST