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