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', '495dj9gt3chvcuvve5ta6ta452', '216.73.216.139', '1770400879', '1770400879', '/product_info.php?XTCsid=1455d70b156c4853db961f68b595bbe7&info=p12_33-feet-crape-paper.html')

[XT SQL Error]