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', 'df80ea473c5ef55be5be9e848a2e921a', '216.73.216.213', '1767295197', '1767295197', '/shop/create_account.php?XTCsid=041c8fc0413f2441df67fe52a6815a15')

[XT SQL Error]