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', '3egh6qg9cc9b696h3p5s7tndg2', '216.73.216.130', '1760879676', '1760879676', '/index.php?XTCsid=ca28ab8f46bb6e791b42fe9b92719761&cat=c4_Beer-Mugs.html')

[XT SQL Error]