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', 'fj9bk44tq4vd5mso6oj12u6tq0', '216.73.216.165', '1752305558', '1752305558', '/product_info.php?info=p6_100-Paper-Plates.html&XTCsid=a48c8beab5e62c5a2ab061d7d44cf227')

[XT SQL Error]