Re: NULLs: theoretical problems?

Quoth Jan Hidders:
> On 24 aug, 14:42, Jon Heggland <jon.heggl..._at_idi.ntnu.no> wrote:

>> But I believe these queries are equivalent:
>>
>> SELECT * FROM t WHERE DEF t.a : t.a = 5
>> SELECT * FROM t WHERE           t.a = 5

I realise that; I meant the second query to be evaluated in normal SQL. What I was trying to say was that in most cases, the only difference between this DEF scheme and regular SQL is that the DEFs force you to handle NULLs explicitly (which I consider a good thing). You still have the excluded middle problem that V. J. Kumar complains about. JOG's apple/banana anecdote isn't quite apt, unless NULL/undefined should be interpreted as "not applicable" instead of "not known".

But anyway: Can potential NULL-ness always be discovered statically?

-- 
Jon