From: "Keith Worthington" <keithw@narrowpathinc.com>
To: "Mark Fenbers" <Mark.Fenbers@noaa.gov>
Cc: pgsql-sql@postgresql.org
Reply-To: KeithW@narrowpathinc.com
Subject: Re: default value for select?
Date: Mon, 9 May 2005 13:26:55 -0400
Message-Id: <20050509172414.M48914@narrowpathinc.com>
In-Reply-To: <427F9685.8050104@noaa.gov>
References: <427F9685.8050104@noaa.gov>
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On Mon, 09 May 2005 12:57:41 -0400, Mark Fenbers wrote
> I want to update a column in myTable. The value this column is set 
> todepends on a nested select statement which sometimes returns 0 
> rowsinstead of 1. This is a problem since the column I'm trying to 
> updateis set to refuse nulls. Here's a sample:
> 
> update myTable set myColumn = (Select altColumn from altTable 
> wherealtColumn != 'XXX' limit 1) where myColumn = 'XXX';
> 
> MyColumn cannot accept nulls, but sometimes "Select altColumn 
> ..."returns 0 rows, and thus, the query fails.
> 
> Is there a way to set a default value to be inserted into myColumn 
> ifand when "select altColumn ..." returns zero rows?
> 
> Mark

Mark,

I do not know if it will work but I would try the COALESCE function.
http://www.postgresql.org/docs/8.0/interactive/functions-conditional.html

Kind Regards,
Keith