Re: By The Dawn's Normal Light

From: Laconic2 <laconic2_at_comcast.net>
Date: Fri, 22 Oct 2004 09:01:25 -0400
Message-ID: <5rudncnyjLwymeTcRVn-rA_at_comcast.com>


"Marshall Spight" <mspight_at_dnai.com> wrote in message news:7IZdd.284714$MQ5.40339_at_attbi_s52...
> "Laconic2" <laconic2_at_comcast.net> wrote in message
news:J_OdnQb_GuO9h-XcRVn-2Q_at_comcast.com...
> >
> > A table represents a set if and only if there is a candidate key.
>
> Saying "at least one" instead of "a" would be less prone to
misunderstanding.
>

Agreed. But I'm about to agree with Paul's objection as well, so this makes it a moot point.

>
> > A Relation is in first normal form if and only if none of the domains of
its
> > attributes permit compound or multivalued values.
>
> This definition is a problem, because it includes two other terms that
> may themselves be subject to confusion: "compound" and "multivalued."
>
> What do those terms mean to you?

I'd rather retreat to the commonly accepted standard, if there is one. I know that TTM modified the definition of 1NF from what it had been previously. What is the "official" definition of 1NF per Date & Darwen? And, does this definition address the issues Dawn raises about what's wrong with 1NF?

I'm hoping to hear from Dawn on this one.

> Distinguishing between ordered and unordered data is *essential.* Data
> has meaning; calling unordered data order means imputing meaning to
> noise; calling ordered data unordered is throwing meaning away.

This is the principal problem I have with the Nelson-Pick model as explained by Dawn in this forum.
"Collections" of like objects are stored in lists in a Pick file. That's the only collecting mechanism there is.
A linked list imposes an order on the collection, whether the order is meaningful or not.

I agree that the question of linked lists is physical, while the question of meaningful ordering is logical. I just haven't figured out a way of disentangling the physical layer from the logical layer in the Nelson-Pick model. And all Dawn will tell us is that Data/Basic is such a cool language that these issues don't matter to the teams that use it.

That's where I get off the bandwagon. Received on Fri Oct 22 2004 - 15:01:25 CEST

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