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', '0ngnm0r5q010j86q9e3dh5c7g2', '216.73.216.70', '1752610104', '1752610104', '/product_info.php?language=de&info=p19_10-Paper-Plates.html&XTCsid=d163dd0fc0b54bf3066f85422c77e00a')

[XT SQL Error]