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

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?

/Peter Received on Wed Sep 20 2006 - 12:12:27 CEST