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From: Laurenz Albe <[email protected]>
To: PALAYRET Jacques <[email protected]>
To: [email protected]
Subject: Re: PostgreSQL  trigger how to detect a column value explicitely modified
Date: Tue, 04 Nov 2025 18:29:05 +0100
Message-ID: <[email protected]> (raw)
In-Reply-To: <[email protected]>
References: <[email protected]>

On Tue, 2025-11-04 at 12:48 +0000, PALAYRET Jacques wrote:
> In a trigger body, is there a simple way to know if a column value has been explicitely modified ?
> Explicitely modified ; in others words, typically indicated in the SET clause of the UPDATE.
> A simple way ; I mean without analysing the SQL statement which can be very difficult according to the statement.

Unless you want to write a C trigger function you can use

  CREATE TRIGGER ... BEFORE|AFTER UPDATE OF col ON tab FOR EACH ROW ...

Then the trigger function will only be called if the SET clause of UPDATE
contains the column "col".

Yours,
Laurenz Albe

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