Re: Reg: Firing Trigger when a particular column value get changed

Thilak babu wrote:
>   I have a scnerio as to fire a trigger when i update a particular column
> in a table. Please do help me out in getting thro this.

The trigger function can use logic to exclude cases where a particular
column does not change. For example:

CREATE FUNCTION "column_update" () RETURNS TRIGGER AS '  BEGIN    IF ( NEW.column <> OLD.column ) THEN
do-your-stuff-here;   END IF;  RETURN NEW;
 
END; ' LANGUAGE 'plpgsql';

CREATE TRIGGER "tg_column_update"  BEFORE UPDATE ON "table_name"  FOR EACH ROW EXECUTE PROCEDURE "column_update" ();

The trigger fires on every update, but the procedure doesn't do
anything unless the particular column changes. I don't think a
trigger can be defined to fire on anything more granular than a
table operation.

Kevin