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', '0v6vqbempcd9gn4kp3mq6fkif7', '216.73.216.188', '1784160573', '1784160573', '/xtshop/product_info.php?info=p943_.html')

[XT SQL Error]