Re: So what's null then if it's not nothing?
Date: Fri, 09 Dec 2005 08:12:56 GMT
Message-ID: <c0bmf.15229$ea6.6209_at_news-server.bigpond.net.au>
vc wrote:
> JOG wrote:
>
>>vc wrote:
>>
>>>Jon Heggland wrote:
>>>
>>>>In article <1134052742.347560.142840_at_o13g2000cwo.googlegroups.com>,
>>>>boston103_at_hotmail.com says...
>>>>
>>>>>>I don't think a "regular" unknown/missing SQL NULL for a 2VL boolean
>>>>>>domain should be regarded a truth value. That would be inconsistent with
>>>>>>how NULL works in other domains.
>>>>>
>>>>>Then the logic ceases to be such if its truth values set include a
>>>>>value for which the equality predicate evaluates to anything other than
>>>>>TRUE or FALSE as I said elsewere.
>>>>
>>>>It does *not* include such a value. NULL is not a truth value any more
>>>>than it is a number or a string.
>>>
>>>I am missing something. If you store/use NULL as a logical value, haw
>>>can it *not* belong to the logical vaue domain with its logical
>>>operations? Sorry, but that does not make sense.
>>
>>[snip]
>>
>>But Null can never _be_ a logical value: it is by definition an
>>indicator of the very absence of a logical value. In addition, as a
>>logical value how could it possibly exist?
> > > I am not sure what point you are trying to make. Are you suggesting > that nulls be allowed in , say, Boolean columns ? Or just the opposite > ?
Try thinking of it this way - the Nulls should not be allowed "in" (because they are not part of the domain) but they force their in anyway (aka gatecrashers). After that you just have to deal with them. Its not that hard - unless you pick a fight, which you will most certainly lose!
Cheers, Frank. Received on Fri Dec 09 2005 - 09:12:56 CET