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', '3o89fvcl7s16l1iikstr15cqa0', '216.73.216.130', '1761225971', '1761225971', '/index.php?XTCsid=a502d5cfc6fa87ac2ae3dc3ad36bf0da')

[XT SQL Error]