example of trigger in postgresql
-- Trigger to update donatiom count in donor table whenever
-- A new donation is made by that person
CREATE or REPLACE FUNCTION increase_count()
RETURNS TRIGGER
AS
$$
BEGIN
UPDATE donor SET dcount = dcount + 1 WHERE did = NEW.did;
END
$$
LANGUAGE plpgsql;
CREATE TRIGGER update_donation_count AFTER INSERT ON donation
FOR EACH ROW
EXECUTE PROCEDURE increase_count();