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Re: UNIQUE not honoured for NULL

From: Andreas Pflug <pgadmin(at)pse-consulting(dot)de>
To: Gaetano Mendola <mendola(at)bigfoot(dot)com>
Cc: Bruno Wolff III <bruno(at)wolff(dot)to>, pgsql-bugs(at)postgresql(dot)org
Subject: Re: UNIQUE not honoured for NULL
Date: 2004-07-12 15:21:51
Message-ID: 40F2AC8F.7050907@pse-consulting.de (view raw or flat)
Thread:
Lists: pgsql-bugs
Gaetano Mendola wrote:
> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA1
> 
> Bruno Wolff III wrote:
> 
> | On Mon, Jul 12, 2004 at 14:47:34 +0200,
> |   Gaetano Mendola <mendola(at)bigfoot(dot)com> wrote:
> |
> |>As someone says NULL = NULL is false
> |
> |
> | As someone else pointed out, NULL = NULL is NULL which is not TRUE.
> 
> Yes, that it's better.

Still not precise.

NULL = NULL
     is NULL (which is neither TRUE nor FALSE)

while
(NULL = NULL) IS NULL
      is TRUE...


Regards,
Andreas

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