Re: 3 value logic. Why is SQL so special?

From: Bob Badour <bbadour_at_pei.sympatico.ca>
Date: Wed, 20 Sep 2006 12:21:57 GMT
Message-ID: <FnaQg.29984$9u.284158_at_ursa-nb00s0.nbnet.nb.ca>

peter koch wrote:

> Bob Badour wrote:
>

>>Chris Lim wrote:
>>

>
>
> [snip]
>
>

>>I can only conclude that you are either a neophyte or a dilettante. The
>>problems with NULL are legion and very well documented elsewhere.
>>
>>NULL confuses reasonably intelligent people because it breaks important
>>identities those people have been conditioned to expect such as:
>>
>>SUM(A) + SUM(B) = SUM(A+B)

>
>
> Why should that identity fail here? Any reasonable implementation of
> NULL would let that identity stand. (I realise this is not the case for
> SQL, but we are not discussing SQL here).
> By the way I have yet to meet a real life computer where the above
> identity holds for arbitrary input so intelligent people should be on
> the watch regardless.
>
>

>>select sum(a) from atable;
>>select sum(b) from atable;
>>select sum(a+b) from atable;
>>
>>In the presense of NULL, those queries violate the identity above.

>
> Again: are you discussing SQL NULL? Is so - why?

Read the title of the thread. Received on Wed Sep 20 2006 - 14:21:57 CEST