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', '11rv6qrs33nrsouars2oeg2jo2', '216.73.216.130', '1760960860', '1760960860', '/shop_content.php?XTCsid=d9aac22dfe7cd4518be7d12dca4112e1&coID=4')

[XT SQL Error]