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', 'gaj7ibhdc1na9c86tlrh20f1g2', '216.73.217.120', '1793528373', '1793528373', '/index.php?XTCsid=38717c4dd62e88001622b2c7b8b8372a&cat=c6_Foodstuffs.html')

[XT SQL Error]