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Re: Update and trigger

From: "A(dot) Kretschmer" <andreas(dot)kretschmer(at)schollglas(dot)com>
To: pgsql-sql(at)postgresql(dot)org
Subject: Re: Update and trigger
Date: 2008-06-11 05:21:07
Message-ID: 20080611052107.GA24984@a-kretschmer.de (view raw or flat)
Thread:
Lists: pgsql-sql
am  Tue, dem 10.06.2008, um 18:45:51 -0700 mailte Medi Montaseri folgendes:
> Hi,
> 
> I need to increament a counter such as myTable.Counter of type integer
> everytime myTable.status a boolean column is updated. Can you help me complete
> this...
> 
> create trigger counter_trigger after update on myTable.counter
> execute procedure 'BEGIN statement; statement; statement END'

much simpler, use a RULE instead a TRIGGER like my example:

Suppose, i have a table called foo, it contains now:

test=# select * from foo;
 i
---
 1
 2
(2 rows)


I create a sequence and a RULE:

test=*# create sequence foo_counter;
CREATE SEQUENCE
test=*# create or replace rule foo_update as on update to foo do also select nextval('foo_counter');
CREATE RULE


And now i do a update on foo:


test=*# update foo set i=2;
 nextval
---------
       1
(1 row)

test=*# update foo set i=3;
 nextval
---------
       2
(1 row)


test=*# select currval('foo_counter');
 currval
---------
       2
(1 row)



Andreas
-- 
Andreas Kretschmer
Kontakt:  Heynitz: 035242/47150,   D1: 0160/7141639 (mehr: -> Header)
GnuPG-ID:   0x3FFF606C, privat 0x7F4584DA   http://wwwkeys.de.pgp.net

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Subject: Re: Update and trigger
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