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', 'n04sq79sk6gr38mfau9n4bmg01', '216.73.216.9', '1758213683', '1758213683', '/index.php?XTCsid=1bfddd293cc0ded97e687a820728d7f1')

[XT SQL Error]