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', '1cbnibn9ujkue52s2auu7lne42', '216.73.216.9', '1757796319', '1757796319', '/product_info.php?XTCsid=0832187515ca706758d8e1ce01e34faf&info=p14_65-drinking-cups-1-2-Liter.html')

[XT SQL Error]