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', 'd4udc72dj9qpiv10ukhhpfe294', '216.73.216.9', '1757782958', '1757782958', '/shop_content.php?XTCsid=a63f52844b6e675f480eaf86612536c2&coID=2')

[XT SQL Error]