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', '5gdjo8vupuhrdk03jbh4jna5o6', '216.73.216.9', '1758209879', '1758209879', '/index.php?XTCsid=84b7343996ba3f4139cecb712f8240ef')

[XT SQL Error]