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From: Josh Berkus <josh@agliodbs.com>
Organization: Aglio Database Solutions
To: Andreas Pflug <Andreas.Pflug@web.de>, pgsql-sql@postgresql.org
Subject: Re: How to notice column changes in trigger
Date: Fri, 7 Mar 2003 09:41:41 -0800
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Andreas,

> 1) update test set a=0 -> trigger does its work
> 2) update test set a=0, b=1, c=2 -> trigger does nothing
> 3) update test set a=0, b=b, c=c -> trigger does nothing, but content of
> a and b dont change either although touched

> IF OLD.b=NEW.b will not work, case 3) will falsely execute the trigger
> code.

I still don't get why you'd want to do this.   Can you provide are real-world 
example where there is a difference between setting B=B and not updating B?

-- 
Josh Berkus
Aglio Database Solutions
San Francisco