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', 'ens3r2r5mu6n7ltdp5fa8u3kk4', '216.73.216.9', '1757982811', '1757982811', '/index.php?XTCsid=c9522ec8d7d3242bfbea3f87266d3e01')

[XT SQL Error]