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', 'tock2lpep9boissb9dhs9n1945', '216.73.216.167', '1762646963', '1762646963', '/product_info.php?XTCsid=ec445a26a1be1b54e711876da9fff244&info=p18_Spa--Hut.html')

[XT SQL Error]