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', '04d17obb1ni5uaopq7pumtbde4', '216.73.216.147', '1751962243', '1751962243', '/index.php?XTCsid=afb4a1ae80caf4f0a7d531c4b0a5325b')

[XT SQL Error]