Re: L

paul c wrote:
> dawn wrote:
> > paul c wrote:
> >> dawn wrote:
> >>> paul c wrote:
> >>>> dawn wrote:
> >>>>> paul c wrote:
> >>>>>> dawn wrote:
> >>>>>>> Hugo Kornelis wrote:
> >>>>>>>> On Fri, 06 Oct 2006 23:29:29 GMT, paul c wrote:
> >>>>>>>>
> >>>>>>>>> Hugo Kornelis wrote:
> >>>>>>>> (snip)
> >>>>>>>>>> Because relational databases supporting NULL *define* it as a marker
> >>>>>>>>>> denoting the absence of a value. Dawn actually makes a good point about
> >>>>>>>>>> context: in C for instance, NULL has a completely different meaning.
> >>>>>>>>>> ...
> >>>>>>>>> Since it has a different meaning in C, there is no point bringing C into
> >>>>>>>>> play here.
> >>>>>>>> Hi Paul,
> >>>>>>>>
> >>>>>>>> The point I was trying to make is that NULL has different meaning in
> >>>>>>>> different context. Using C as example was a bad choice, since it
> >>>>>>>> obfuscated what I was trying to convey, rather than clarifying it.
> >>>>>>>>
> >>>>>>>> The meaning of NULL in the context of SQL is also quite different from
> >>>>>>>> the meaning of NULL in Pick (and possibly other MV databases). That's
> >>>>>>>> what I wanted to write, and what I should have written in the first
> >>>>>>>> place. Much of the discussion between Cimode and Dawn appears (as I read
> >>>>>>>> it) to come from Cimode talking aboout SQL NULL and Dawn talking about
> >>>>>>>> Pick NULL - but they both think that the other is discussing the same
> >>>>>>>> NULL.
> >>>>>>> Thanks for giving your take on that, Hugo, since I was clearly getting
> >>>>>>> nowhere.
> >>>>>> What else is new.
> >>>>>>
> >>>>>> You won`t get anywhere as long as you keep comparing apples to oranges,
> >>>>>> eg., imagining that Pick has a data model that is comparable to what
> >>>>>> Codd had in mind.
> >>>>> That is not what this was about, Paul.
> >>>> Yes, it is, see below.
> >>>> There are many languages that
> >>>>> employ 2VL. SQL is the odd-ball out.
> >>>> You are still talking languages, not r.d. Theory.
> >>> I would think you could abstract from that statement.
> >>>
> >>>> Too bad I can`t quote Codd here.
> >>> His approach to NULL is something that many disagree with today, right?
> >>> Think how many hours and dollars the implementation of this approach
> >>> to NULL has cost the industry. Of course one can define NULL this way,
> >>> but the costs outweigh the benefits in doing so. --dawn
> >>>
> >>>> But just in an effort to get you on a
> >>>> more useful track, did SQL endorse Nulls before or after Codd`s 1979
> >>>> paper (question mark intended, sorry the keyboard is fine, something to
> >>>> do with whatever Mozilla is doing to firefox or thunderbird).
> >>
> >> Not interested in the editorial. Would rather you go and find out the
> >> answer to my question.
> >>
> >> p
> >
> > In order to get the L out of here (where did that subject name come
> > from?), I'll give a guess as I'm not likely to research that right now.
> > [I messed up my ACM membership by signing up for the portal through
> > IEEE and lost access to stuff. I shouldn't do my own admin!]
> >
> > My guess is that the SQL NULL was likely in System/R in 1978, but even
> > if that is the case, it does not mean it was developed independently of
> > Codd. Was '79 his first publication on the topic? When did his 4VL
> > paper come out? --dawn
> >

>
>

At first I thought you knew the answer and just didn't want to tell me, then I thought you wanted to know the answer and didn't. Ah well. In case it wasn't clear, I do not know the answer to your question. I do think questions about history are interesting and do think it matters, which is why I didn't say precisely what you suggested. <end of topic, I hope> Received on Tue Oct 10 2006 - 04:05:16 CEST