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', '12kll4f3s1it6g7mdvj1pujc04', '216.73.216.118', '1761588584', '1761588584', '/product_info.php?XTCsid=502c4d4f7753d1888d9a6ca985d5c9c9&info=p16_Octoberfest-CD.html')

[XT SQL Error]