Re: Proposal: 6NF

JOG wrote:
> On Oct 9, 2:56 pm, "dawn" <dawnwolth..._at_gmail.com> wrote:
> > J M Davitt wrote:
> > > Jan Hidders wrote:
> > > > J M Davitt schreef:
> >
> > > >>dawn wrote:
> >
> > > >>>Given the definition of NULL that I typically use (with non-SQL based
> > > >>>solutions), NULL is a value and can be modeled mathematically with the
> > > >>>empty set. In that case, a relation tuple with a NULL is as valid
> > > >>>mathematically as one without. Agreed? --dawn
> >
> > > >>Well, if it's merely a matter of definition, then, "No. Not agreed."
> >
> > > > Since Dawn defines NULL as the empty set your answer implies that you
> > > > think the empty set is not a value. Why?
> >
> > > > -- Jan Hidders
> >
> > > Partly (i) NULL is already overusedI am using it only one of the ways it is used, unless I qualify it as
> > "SQL NULL" which is quite different from most other uses of NULL within
> > the s/w development profession.
> >
> > > and (ii) the language
> > > used on this thread is imprecise.All language is imprecise. We always make assumptions about what the
> > other person be able to intrepret as it is intended. When there are
> > differences of opinion, then it is helpful to increase precision in the
> > definitions.
> >
> > > For instance, the reference to "relation tuple" in the
> > > above paragraph: is she distinguishing between tuples
> > > in relations and tuples otherwise? I was responding to JOG's statement
> > > "A relation tuple with a NULL in it is no relation tuple at all. From a mathematical perspective,
> > > case closed. "So I used the same language.
> >
> > > What, exactly, does
> > > "valid mathematically" have to do with her point?
> >
> > [I realize I'm arguing against a point not explicitly made.] I was responding to JOG:
> > > "A relation tuple with a NULL in it is no relation tuple at all. From a mathematical
> > > perspective, case closed. "
> > indicating that the this depends on the def of NULL. The case is
> > closed from a mathematical perspective on an SQL NULL (which, I think,
> > was JOG's point), but because he did not qualify or define the NULL, I
> > wanted to be clear that the case is not closed on the use of NULL with
> > databases, in general. That depends on the def of NULL.

>

In retrospect, agreed. Perhaps one more person has a clue that the SQL NULL is not the only nor the original NULL, for what it is worth. Hopefully this will be more relevant in the dbms world again soon (over the coming decade?) Although there isn't agreement, there does seem to be momentum from many places to head (back to) 2VL with DBMS's. Knock on wood. The installed base is obviously a huge obstacle. --dawn Received on Tue Oct 10 2006 - 01:30:09 CEST