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To: Neil Harkins <nharkins@well.com>
cc: pgsql-sql@postgresql.org
Subject: Re: concatenation with a null column (using ||) nulls the result? 
In-reply-to: <Pine.SOL.4.10.10604101430250.2779-100000@well.com> 
References: <Pine.SOL.4.10.10604101430250.2779-100000@well.com>
Comments: In-reply-to Neil Harkins <nharkins@well.com>
	message dated "Mon, 10 Apr 2006 14:36:47 -0700"
Date: Mon, 10 Apr 2006 17:47:26 -0400
Message-ID: <921.1144705646@sss.pgh.pa.us>
From: Tom Lane <tgl@sss.pgh.pa.us>
X-Archive-Number: 200604/66
X-Sequence-Number: 24875

Neil Harkins <nharkins@well.com> writes:
> Is this standard SQL behavior? 

Yes.  SQL92 6.13 <string value expression>, general rule 2:

         2) If <concatenation> is specified, then let S1 and S2 be the re-
            sult of the <character value expression> and <character factor>,
            respectively.

            a) If either S1 or S2 is the null value, then the result of the
              <concatenation> is the null value.

		...

			regards, tom lane