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', 'pm95ge9unp1f5hnjj3a81cnt20', '216.73.216.80', '1751325031', '1751325031', '/index.php?XTCsid=a62bc14a2472a2e20215fc39a8dcda1a')

[XT SQL Error]