Re: L

From: paul c <toledobythesea_at_oohay.ac>
Date: Tue, 10 Oct 2006 00:49:20 GMT
Message-ID: <k6CWg.116248$1T2.100514@pd7urf2no>

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 Received on Mon Oct 09 2006 - 19:49:20 CDT