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', 'e4cp3g5itf50rh5slc1c6hvkt5', '216.73.216.28', '1775725149', '1775725149', '/shop_content.php?XTCsid=a63f52844b6e675f480eaf86612536c2&coID=4')

[XT SQL Error]