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', 'utof1ohrhpjvq0sekm7f1na150', '216.73.216.70', '1752612311', '1752612311', '/product_info.php?info=p16_Octoberfest-CD.html&XTCsid=6434a50ec6def965fd2bb3c4699fde82')

[XT SQL Error]