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', '466k8qc6b7q88t3oah37r4emj2', '216.73.216.9', '1758030402', '1758030402', '/product_info.php?XTCsid=c407ede434192d8d024c7c2f06b2be8c&info=p21_Paper-tablecloth-10-meters.html')

[XT SQL Error]