Re: difference between EXCEPT and NOT IN?

On Tue, Apr 1, 2008 at 6:04 PM, Stephan Szabo
<sszabo(at)megazone(dot)bigpanda(dot)com> wrote:
> On Tue, 1 Apr 2008, Raphael Bauduin wrote:
>
> > The 2 following statements don't give the same result. I expected the
> > second ti give the exact same result as the first one.
>
> If any entree_id can be NULL they aren't defined to give the same result.
>
> EXCEPT is defined in terms of duplicates based on distinctness, and for
> example (1 is distinct from 1) is false, (1 is distinct from NULL) is true
> and (NULL is distinct from NULL) if false.
>
> NOT IN is defined in terms of equality, and for example, (1=1) is true,
> (1=NULL) is unknown and (NULL=NULL) is unknown.
>

My problem came from 2 entries in the table postes that had an entree_id NULL

Thanks for your fast answer, it has helped me spot the problem!

Raph

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