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Re: Trigger.. AFTER and BEFORE with specific column changed

From: Adrian Klaver <adrian(dot)klaver(at)gmail(dot)com>
To: Albert <oo_O2_oo(at)hotmail(dot)com>
Cc: pgsql-general(at)postgresql(dot)org
Subject: Re: Trigger.. AFTER and BEFORE with specific column changed
Date: 2012-04-01 19:13:23
Message-ID: 4F78A8D3.8040504@gmail.com (view raw or flat)
Thread:
Lists: pgsql-general
On 04/01/2012 11:45 AM, Albert wrote:
> *I'm trying to follow this :*
>
>
> CREATE TRIGGER check_update
>      *BEFORE* UPDATE ON accounts
>      FOR EACH ROW
>      WHEN (OLD.balance IS DISTINCT FROM NEW.balance)
>      EXECUTE PROCEDURE check_account_update();
>
> *but with AFTER instead of BEFORE. and I'm keep getting error on or near
> WHEN.

What is the error message?

> does that because i have to use BEFORE ? what if i need to execute the
> procedure after updating column and it has really changed.*

Depends what the procedure is doing. For more detail on what the WHEN 
does in BEFORE and AFTER triggers see here:
http://www.postgresql.org/docs/9.0/interactive/sql-createtrigger.html

Look for the Notes section.

>
> --
> View this message in context: http://postgresql.1045698.n5.nabble.com/Trigger-AFTER-and-BEFORE-with-specific-column-changed-tp5610712p5610712.html
> Sent from the PostgreSQL - general mailing list archive at Nabble.com.
>


-- 
Adrian Klaver
adrian(dot)klaver(at)gmail(dot)com

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