Message-ID: <20040510213856.65983.qmail@web20812.mail.yahoo.com>
Date: Mon, 10 May 2004 14:38:56 -0700 (PDT)
From: Jeff Eckermann <jeff_eckermann@yahoo.com>
Subject: Re: Trigger function to know which fields are being updated
To: Bernard Cheung <cheungsw@hotmail.com>, pgsql-sql@postgresql.org
In-Reply-To: <BAY1-F8NsokLQ8aZRhQ0000aa28@hotmail.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii


--- Bernard Cheung <cheungsw@hotmail.com> wrote:
> I am writing a trigger function. How can I know
> which fields are being 
> updated in the PL/SQL function?
> 
> For example I have a table here:
> 
> 
> CREATE TABLE COMPANY (
>   COMPANY_ID VARCHAR(10) NOT NULL,
>   NAME VARCHAR(30),
>   ADDRESS VARCHAR(30));
> 
> I want to write a trigger to block all update
> statements without updating 
> NAME. I tried the following code block and it
> doesn't work:
> 
> 
>   IF TG_OP = ''UPDATE'' THEN
>      IF NEW.NAME IS NULL THEN
>         RAISE NOTICE ''Field NAME must be
> provided!'';
>      END IF;
>   END IF;

That should work.  Perhaps "name" is not actually
null, but rather an empty string?  In that case, your
test needs to be: "IF NEW.NAME IS NULL OR NEW.NAME =
'''' THEN..."

> 
> Are there any functions like the Oracle's UPDATING()
> predicate?
> 
> Bernard Cheung
> 
>
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