Date: Tue, 30 Jan 2007 11:38:34 -0500
From: "D'Arcy J.M. Cain" <darcy@druid.net>
To: Andrew Sullivan <ajs@crankycanuck.ca>
Cc: pgsql-sql@postgresql.org
Subject: Re: Differentiate Between Zero-Length String and NULLColumn
 Values
Message-Id: <20070130113834.fa8d09e0.darcy@druid.net>
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	<20070130142332.GA31905@phlogiston.dyndns.org>
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On Tue, 30 Jan 2007 09:23:32 -0500
Andrew Sullivan <ajs@crankycanuck.ca> wrote:
> Hmm.  Well, I'm not an Oracle guy, so I don't really know.  All I
> know is that we occasionally get people coming from Oracle who are
> surprised by this difference.  What I've been _told_ is that '' and
> NULL are under some circumstances (maybe integers?) the same thing,
> whereas of course ' ' and NULL are not.  But since I'm not an Oracle
> user, people should feel free to ignore me :)

I don't have an Oracle installation here and I haven't used it much but
I wonder if they treat the following two statements differently.

   SELECT * FROM table WHERE column IS NULL;
   SELECT * FROM table WHERE column = NULL;

The latter violates the SQL spec and is not allowed by PostgreSQL
without setting a special flag.  Is it possible that Oracle accepts "="
against NULL and also treats it slightly differently?

-- 
D'Arcy J.M. Cain <darcy@druid.net>         |  Democracy is three wolves
http://www.druid.net/darcy/                |  and a sheep voting on
+1 416 425 1212     (DoD#0082)    (eNTP)   |  what's for dinner.