1366 - Incorrect integer value: '' for column 'customer_id' at row 1

insert into whos_online (customer_id, full_name, session_id, ip_address, time_entry, time_last_click, last_page_url) values ('', 'Guest', '97c7peti7mv4st1rdjihd28e12', '216.73.216.6', '1763806394', '1763806394', '/xtshop/product_info.php?info=p940_.html')

[XT SQL Error]