CREATE TRIGGER log_create_edit_product
AFTER INSERT OR UPDATE OF title, price, unit, content, additions,  hint, cover, description -- ONLY Certain fields
ON public.product
FOR EACH ROW
WHEN (OLD.balance IS DISTINCT FROM NEW.balance)     -- Condition! Optional
-- OR: 
-- WHEN (OLD.* IS DISTINCT FROM NEW.*)
-- WHEN (OLD.price > 100)
-- WHEN (NEW.title = 'hello' AND NEW.price < 20::money)
EXECUTE PROCEDURE public.log_create_edit_product();


CREATE FUNCTION public.log_create_edit_product()
    RETURNS trigger
    LANGUAGE 'plpgsql'

AS $BODY$
BEGIN 

    INSERT INTO product_history
    (action, aid, pid, title, price, unit, content, additions, rpids, tids, hint, cover, description) VALUES
    (if_else(TG_OP = 'INSERT', ':create'::action, ':edit'::action), COALESCE(NEW.editor_aid, NEW.creator_aid), NEW.id, 
     NEW.title, NEW.price, NEW.unit, NEW.content, NEW.additions, NEW.rpids, NEW.tids, NEW.hint, NEW.cover, NEW.description);
    
    IF (TG_OP = 'INSERT') THEN
        INSERT INTO product_stat (pid, count_edit, title) values (new.pid, 1, new.title);
    ELSE 
        UPDATE product_stat SET count_edit = count_edit + 1, last_update = present(), title = new.title
        WHERE pid = new.id;
    END IF;

    RETURN NEW;

END;