Re: L
Date: Tue, 10 Oct 2006 01:48:18 GMT
Message-ID: <CZCWg.117228$5R2.69131_at_pd7urf3no>
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 >
instead of wasting time with admitted guesses, why don`t you just answer the question and say you don`t know and you have no idea why it matters. your topic seems to be newsgroup rhetoric, not c.d.t.
p Received on Tue Oct 10 2006 - 03:48:18 CEST