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', 'v8b956r2lga6m9p0k3mulel1m6', '216.73.217.25', '1781319401', '1781319401', '/product_info.php?XTCsid=979063553d403df75eb8c32c59325da8&info=p2_Bavarian-Pennant-Chain.html')

[XT SQL Error]