sql - in mysql trigger.. how to use insert into and update query -

i have product_price_log table. updated ever new price updated in product_price table.

i using trigger:

drop trigger if exists product_update;   delimiter $$ create trigger product_update before update on w3xab_virtuemart_product_prices each row begin declare virtuemart_product_id int; declare old_product_price decimal(15,5) default 0; declare new_product_price decimal(15,5) default 0; declare price_update_date date;  if (new.product_price <> old.product_price)   insert product_price_log (virtuemart_product_id,old_product_price, new_product_price,  price_update_date) values (new.virtuemart_product_id, old.product_price, new.product_price, curdate()) on duplicate key update  old_product_price = values(old.product_price), new_product_price = values(new.product_price), price_update_date = curdate();   end if;     end$$     delimiter ; 

now no error..but update not working when try update price... insert working

i set virtuemart_product_id primay key dont know whats going m totally stuck @ point... cant understand why not updating..

i don't think can values(curdate()) since isn't column name. try price_update_date=curdate()