Re: So what's null then if it's not nothing?
From: Alexandr Savinov <spam_at_conceptoriented.com>
Date: Mon, 19 Dec 2005 10:45:49 +0100
Message-ID: <43a68170$1_at_news.fhg.de>
>
>
> "2 + NULL" isn't a valid expression. (Well, it is in SQL(?), but I don't
> think it should be, and I won't try to justify it.)
Date: Mon, 19 Dec 2005 10:45:49 +0100
Message-ID: <43a68170$1_at_news.fhg.de>
Jon Heggland schrieb:
> In article <1134926774.703015.67240_at_z14g2000cwz.googlegroups.com>,
> boston103_at_hotmail.com says...
>
>>Sure, a one-argument predicate like 'is_null', or 'is_odd', talks >>about a property/attribute and can be called an 'adjective'. But the >>'is_null' predicate cannot help one answer the question "what is '+' in >>'2 + NULL' ?". So, what is '+' in the expression and how does one >>interpret such expression ?
>
>
> "2 + NULL" isn't a valid expression. (Well, it is in SQL(?), but I don't
> think it should be, and I won't try to justify it.)
2 + NULL = 2 Just remove NULL because it is a flag to denote a non-existing thing (which exists in other dimensions but does not exist here in the current dimension). So there are neither formal nor informal problems with this expression if we provide correct interpretation of NULL. Notice that NULL here (and always) in not number 0. In the expression 2+NULL we do not apply the operation at all, while in 2+0 we do apply the sum operation.
-- http://conceptoriented.comReceived on Mon Dec 19 2005 - 10:45:49 CET