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', 'p9tdqjksocdiqn3g04mt3prg51', '216.73.217.92', '1777449198', '1777449198', '/index.php?XTCsid=a0c8d0b3d08cb472c84559a313755d47&cat=c4_Beer-Mugs.html')

[XT SQL Error]