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', 'fhcg3bdl17rib36a5si2nifi34', '216.73.216.244', '1752205239', '1752205239', '/product_info.php?language=en&info=p14_65-drinking-cups-1-2-Liter.html&XTCsid=a63f52844b6e675f480eaf86612536c2')

[XT SQL Error]