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', 'm4es84rfi6i921aa1feutbpbk1', '216.73.216.9', '1758153166', '1758153166', '/product_info.php?XTCsid=b4e317ab79f3ee4221fe0e84cc3a81a4&info=p19_10-Paper-Plates.html&language=de')

[XT SQL Error]