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', '0k2ltpge7jvc912vfbg9j0caj0', '216.73.216.7', '1758229720', '1758229720', '/product_info.php?XTCsid=ca28ab8f46bb6e791b42fe9b92719761&info=p14_65-drinking-cups-1-2-Liter.html')

[XT SQL Error]