Re: Proposal: 6NF

From: paul c <toledobythesea_at_oohay.ac>
Date: Tue, 10 Oct 2006 00:32:28 GMT
Message-ID: <wSBWg.116115$1T2.76348@pd7urf2no>

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.

Too bad I can`t quote Codd here. 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).

p Received on Mon Oct 09 2006 - 19:32:28 CDT