From: Raphael Bauduin <rblists@gmail.com>
To: Stephan Szabo <sszabo@megazone.bigpanda.com>
Cc: pgsql-sql@postgresql.org
Subject: Re: difference between EXCEPT and NOT IN?
Date: Tue, 1 Apr 2008 18:43:47 +0200
Message-ID: <f5227160804010943m723de307g3aa51adeb17419a2@mail.gmail.com> (raw)
In-Reply-To: <20080401085733.F16796@megazone.bigpanda.com>
References: <f5227160804010850q74063e22t644ea4274c67730d@mail.gmail.com>
<20080401085733.F16796@megazone.bigpanda.com>
On Tue, Apr 1, 2008 at 6:04 PM, Stephan Szabo
<sszabo@megazone.bigpanda.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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To: pgsql-sql@postgresql.org
Cc: rblists@gmail.com, sszabo@megazone.bigpanda.com
Subject: Re: difference between EXCEPT and NOT IN?
In-Reply-To: <f5227160804010943m723de307g3aa51adeb17419a2@mail.gmail.com>
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