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', 'kgq2qutcrp10lgvr8t04tu1gf2', '216.73.216.9', '1758161928', '1758161928', '/shop_content.php?XTCsid=1455d70b156c4853db961f68b595bbe7&coID=3')

[XT SQL Error]