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

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

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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.

>
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>

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

*i get:*

Syntax error at or near 'WHEN'
LINE 1: ... check_update AFTER UPDATE ON accounts FOR EACH ROW WHEN
(OLD.balance IS DISTINCT FROM NEW.balance) ....

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On 04/01/2012 10:10 PM, Albert wrote:
> *i get:*
>
> Syntax error at or near 'WHEN'
> LINE 1: ... check_update AFTER UPDATE ON accounts FOR EACH ROW WHEN
> (OLD.balance IS DISTINCT FROM NEW.balance) ....

Hmmm. So two questions:

What happens if you copy the example in the docs exactly and use NEW.*
and OLD.*?

What is the table definition for accounts?

>
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> Sent from the PostgreSQL - general mailing list archive at Nabble.com.
>

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

Albert <oo_O2_oo(at)hotmail(dot)com> writes:
> *i get:*
> Syntax error at or near 'WHEN'
> LINE 1: ... check_update AFTER UPDATE ON accounts FOR EACH ROW WHEN
> (OLD.balance IS DISTINCT FROM NEW.balance) ....

Does the BEFORE case work for you either? I'm suspicious that you
are using a PG version that predates WHEN-clause support in triggers.

regards, tom lane