Re: Does Codd's view of a relational database differ from that ofDate& Darwin? [M.Gittens]

"Alfredo Novoa" <alfredo_novoa_at_hotmail.com> wrote in message news:32vaa1l02d4hu4p2h8asm0hbb9vopi82um_at_4ax.com...
> On Mon, 06 Jun 2005 16:23:13 +0100, Paul <paul_at_test.com> wrote:
>
>>OK so basically the problem is with aggregates?
>
> The problem is basically with queries, but aggregate queries are
> probably the most problematic when we allow nulls.

Nulls exist in set theory, they exist in the real world, and they exist in data elements. While they may be problematic, their problematics can be effectively managed and resolved.

>>Why not say then that all aggregates that involve a NULL return NULL?
>
> This is what SQL does. Sometimes we want to get a value but we get a
> null instead.

This is user-definable in TSQL by use of the command SET CONCAT_NULL_YIELDS_NULL { ON | OFF }
> I have to mantain an application that breaks very often due to this
> problem.

Find the corresponding SET command.
Which SQL-DBMS is it?

-- 
Pete Brown
IT Managers & Engineers
Falls Creek
Australia
www.mountainman.com.au