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', 'vjkumgh44492j6c34l36bm8pm6', '216.73.216.9', '1758043120', '1758043120', '/index.php?XTCsid=a63f52844b6e675f480eaf86612536c2&cat=c6_Foodstuffs.html')

[XT SQL Error]