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', 'd2q375k4h32rhctp19459buoe5', '216.73.216.165', '1752306593', '1752306593', '/index.php?cat=c2_Decoration.html&XTCsid=a8f768c639dfd62c2d6d3cd7ed21b720')

[XT SQL Error]