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', 'c6cqrv8664c1qauv90gkfldss0', '216.73.216.147', '1751744394', '1751744394', '/shop_content.php?coID=7&XTCsid=a8f768c639dfd62c2d6d3cd7ed21b720')

[XT SQL Error]