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', 'bd9b9ed5883f2f880812f82050d4863e', '216.73.216.213', '1767296769', '1767296769', '/shop/product_info.php?info=p131_.html')

[XT SQL Error]