Re: BUG #6669: unique index w/ multiple columns and NULLs

Jeff Davis wrote:
> On Mon, 2012-06-04 at 11:56 -0400, Bruce Momjian wrote:
>   
>> I get your point about COUNT(*) really counting rows, not values, but
>> why doesn't GROUP BY then skip nulls?
>>     
>
> A while ago, I came to the conclusion that applying logic to extrapolate
> the behavior of NULL is a bad idea:
>
> http://thoughts.davisjeff.com/2009/08/02/what-is-the-deal-with-nulls/
>
> Jose was not wrong about the inconsistency between UNIQUE and GROUP BY.
> But the answer is that "we do it that way because the standard says so".
> And that's a good reason.
>
> Regards,
> 	Jeff Davis
>
>
>   
The article pointed by Jeff is very insightful.

NULLs, if you know them, avoid them :-(

I agree with Date and Darwen about NULLs:

"Chris Date and  Hugh Darwen the authors of The Third Manifesto, have 
suggested that the SQL Null implementation is inherently flawed and 
should be ELIMINATED altogether^ 
 
, pointing to inconsistencies and flaws in the implementation of SQL 
Null-handling (particularly in aggregate functions) as proof that the 
entire concept of Null is flawed and should be removed from the 
relational model"

j