Date: Tue, 30 Jan 2007 08:13:34 -0500
From: Andrew Sullivan <ajs@crankycanuck.ca>
To: pgsql-sql@postgresql.org
Subject: Re: Differentiate Between Zero-Length String and NULL Column Values
Message-ID: <20070130131334.GD31676@phlogiston.dyndns.org>
References: <016d01c74430$043b1b90$9b0014ac@wbaus090>
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On Tue, Jan 30, 2007 at 04:32:22PM +1100, Phillip Smith wrote:
> SHAMPOO","EQUEST","401600","0.00","0.00","0.00","0.00","10.00",""
                                                                 ^^
> 	SELECT * FROM tmpstk WHERE ean = NULL;
                                         ^^^^

Along with what Michael Fuhr said in his post about equality and
NULL, Postgres doesn't treat the empty string and NULL as equivalent
(because they're not).  Only Oracle has that dodgy interpretation of
SQL, as far as I know.  If you want to use the empty string, you need 

	WHERE ean = ''

If you want instead ean to be NULL, use the traditional \N to signify
NULL on your way in, or define null some other way.

A

-- 
Andrew Sullivan  | ajs@crankycanuck.ca
Users never remark, "Wow, this software may be buggy and hard 
to use, but at least there is a lot of code underneath."
		--Damien Katz