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', 'g7bcgj7dg51dhrtvc1vfsk2q85', '216.73.216.155', '1767607388', '1767607388', '/index.php?XTCsid=1ce6d0a6925740e42ccf6986944a240a&cat=c4_Beer-Mugs.html')

[XT SQL Error]