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', 'k49af7eplr4g3crhribqcn8c76', '216.73.216.180', '1766436771', '1766436771', '/shop_content.php?XTCsid=98fab66f7c5bcfa7f4c82f0bdb1cf869&coID=4')

[XT SQL Error]