Re: 3vl 2vl and NULL

From: David Cressey <>
Date: Sat, 18 Feb 2006 12:36:49 GMT
Message-ID: <BxEJf.208$F94.78_at_trndny02>

"Marshall Spight" <> wrote in message
> dawn wrote:
> > Marshall Spight wrote:
> > > >
> > > > I am using the meaning of the term when the term was coined for use
> > > > with data. I can point to the appropriate references each time I
> > > > the term so that there is not misunderstanding. We have the same
> > > > problem with 1NF as Date now has that include relation-valued
> > > > attributes.
> > >
> > > I really don't think it's a good idea to base your terminological
> > > choices on what was current in 1970.
> >
> > I looked for the last time that there seemed to be general agreement
> > ;-)



> > > By that metric, when you say "a modern
> > > statically typed language" I should understand you to mean Fortran or
> > > Cobol. Instead, I think you should use terminology in a way that is
> > > current. It is of course your choice.
> >
> > Although Date now defines 1NF differently, I think he has been
> > consistent in defining "normalization" to be equivalent to 1NF. p149
> > An Introduction to Database Systems 8e. What are the definitions
> > competing with this one (which seems to include Codd, Date, Darwen,
> > Pascal and others) and who should I look to for the best definitions
> > from those camps? Even if I use the terms consistent with Codd, I can
> > at least give a nod to other definitions.

> I guess I'm not much interested in figuring out what the authorities
> (or authority-wannabes) say. It seems to me that if you want a
> term for relations with further structure that just the classical
> definition of 1NF, you could say "nested relations" and stand a
> pretty good chance of being understood. Anyway, if we're trying
> to figure out what we'd like in a system, we should probably be
> saying exactly what the features are rather than relying on
> very broad terms.

> > Gotta run, I'll try to catch the rest later.

> Marshall



Under most circumstances, I would agree with your earlier point that using 1970 terminology is bad phrasing, when compared to using current terminology.

The problem, in this case, is that current terminology with regard to 1NF is divided, among data modellers, on precisely the point that Dawn wishes to discuss: the elimination of repeating groups as a first step in normalizing a schema or relations.

According to the way many of us (I include myself) use the terminology, putting a relation into 1NF implies decomposing, when necessary, in order to express repeating groups as sets of tuples, in separate relations.

There is a large body of other professionals, who use the term 1NF differently, and would claim that a schema of relations is already in 1NF, even if there are repeating groups. If I'm not greatly mistaken, the quote cited from Date's introduction defines 1NF precisely this way.

Given this state of affairs, Dawn's choice strikes me as making the best of a bad situation, and not as bad phrasing on her part. Received on Sat Feb 18 2006 - 13:36:49 CET

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