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', 'jviesra9dif5l9815mjaiivqr1', '216.73.216.197', '1751515002', '1751515002', '/index.php?XTCsid=ab03471f42454d4861477a2c9487ae4f')

[XT SQL Error]