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', 'b7h29vvrbg017vp5sjug98vm61', '216.73.216.9', '1758035367', '1758035367', '/index.php?XTCsid=ca28ab8f46bb6e791b42fe9b92719761&cat=c4_Beer-Mugs.html')

[XT SQL Error]