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List:       postgresql-general
Subject:    Re: [HACKERS] [SQL] CREATE RULE ON UPDATE/DELETE
From:       Bruce Momjian <pgman () candle ! pha ! pa ! us>
Date:       2001-11-29 22:17:39
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I have added the following text to the CREATE TRIGGER manual page to
address this issue.  It often confuses people so it is good to point
out:

  <para>
  <command>SELECT</command> does not modify any rows so you can not
  create <command>SELECT</command> triggers.
  </para>


---------------------------------------------------------------------------

> Yes, I agree perfectly... I never thought of that! I would really like it if some \
> more info was added to the docs regarding info on rules and triggers. The section \
> on update rules is quite good, but some more would never hurt. One point in the \
> trigger vs rules section which at least to me is very important is the simple fact \
> that you cannot have a trigger on a select... Ok I understand why - but it took \
> some time... 
> Thank you for answering my questions!
> 
> regards,
> 
> Aasmund.
> On Sun, 21 Oct 2001 12:47:41 -0400, Tom Lane <tgl@sss.pgh.pa.us> wrote:
> > Joel Burton <joel@joelburton.com> writes:
> > 
> > 
> > Surely you'd need something like
> > 
> > CREATE RULE dbl_update AS ON UPDATE TO dbl DO INSTEAD UPDATE raw SET
> > id = NEW.id / 2, name = NEW.name WHERE OLD.id = id * 2;
> > 
> > (untested...)
> > 
> > 			regards, tom lane
> 
> Aasmund Midttun Godal
> 
> aasmund@godal.com - http://www.godal.com/
> +47 40 45 20 46
> 
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-- 
  Bruce Momjian                        |  http://candle.pha.pa.us
  pgman@candle.pha.pa.us               |  (610) 853-3000
  +  If your life is a hard drive,     |  830 Blythe Avenue
  +  Christ can be your backup.        |  Drexel Hill, Pennsylvania 19026

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