From: Herouth Maoz <herouth@tippcom.co.il>
To: pgsql-sql@postgresql.org
Subject: Re: Differentiate Between Zero-Length String and NULLColumn Values
Date: Tue, 30 Jan 2007 16:37:43 +0200
Message-ID: <200701301637.43897.herouth@tippcom.co.il> (raw)
In-Reply-To: <20070130142332.GA31905@phlogiston.dyndns.org>
References: <20070130131334.GD31676@phlogiston.dyndns.org>
<45BF584F.A3DD.0030.0@indicator.be>
<20070130142332.GA31905@phlogiston.dyndns.org>
Andrew Sullivan Wrote:
> On Tue, Jan 30, 2007 at 02:38:07PM +0100, Bart Degryse wrote:
> > 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.
>
> 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 :)
Sybase does something like that... In sybase, null and empty string are the
same. However, to avoid the equality ''=NULL, they actually interpret '' as a
single space. So if you do something like SELECT 'A'+''+'C' (concatenation is
+ in sybase), it results in 'A C'. Null is a "real" empty string in that its
length is zero, and if you insert a trim('') into a column, it will treat it
as NULL.
Herouth
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To: pgsql-sql@postgresql.org
Cc: herouth@tippcom.co.il
Subject: Re: Differentiate Between Zero-Length String and NULLColumn Values
In-Reply-To: <200701301637.43897.herouth@tippcom.co.il>
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