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', 't9og8q53dse1tpkgspjj1k8q00', '216.73.216.9', '1758177361', '1758177361', '/shop_content.php?XTCsid=3e3fcef0642c69bbf707de3c0bc1cf9c&coID=8')

[XT SQL Error]