Re: Differentiate Between Zero-Length String and NULLColumn Values

From: "Bart Degryse" <Bart(dot)Degryse(at)indicator(dot)be>
To: <pgsql-sql(at)postgresql(dot)org>
Subject: Re: Differentiate Between Zero-Length String and NULLColumn Values
Date: 2007-01-30 13:38:07
Message-ID: 45BF584F.A3DD.0030.0@indicator.be
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Andrew, I think you're wrong stating that Oracle would interpret NULL and empty string as equal.
The Oracle databases I use (8, 9 and 10) certainly make a distiction between both values.
Maybe earlier versions did so, that I don't know.

>>> Andrew Sullivan <ajs(at)crankycanuck(dot)ca> 2007-01-30 14:13 >>>
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(at)crankycanuck(dot)ca
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to use, but at least there is a lot of code underneath."
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