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', '4hmloanm3fvnqgtor17smpe9d6', '216.73.216.141', '1751425963', '1751425963', '/index.php?XTCsid=d19d8dd01df36fa1fc7665199815414d')

[XT SQL Error]