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', 'iqnvvn1klbllt6s730sdalqt92', '216.73.217.120', '1793571751', '1793571751', '/product_info.php?XTCsid=e65207aee44f142683bacdd3544c84a8&info=p2_Bavarian-Pennant-Chain.html')

[XT SQL Error]