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', '9n48d9v87r6kel2q9ib57qjv95', '216.73.216.180', '1766690400', '1766690400', '/shop_content.php?XTCsid=679e5364f8ebcbd98062f6d07b727e6d&coID=1')

[XT SQL Error]