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', 'fp5vu4ssrss3lo4v7d9746unr3', '216.73.216.110', '1752053511', '1752053511', '/product_info.php?info=p14_65-drinking-cups-1-2-Liter.html&XTCsid=67a1ee4a966bad4e2954e4e321814afb')

[XT SQL Error]