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From: paul c <toledobythesea_at_oohay.ac>
Date: Tue, 10 Oct 2006 00:30:49 GMT
Message-ID: <ZQBWg.116091$1T2.51984_at_pd7urf2no>
>>>> 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.
Date: Tue, 10 Oct 2006 00:30:49 GMT
Message-ID: <ZQBWg.116091$1T2.51984_at_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 Tue Oct 10 2006 - 02:30:49 CEST