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', '1cd45s1665ubqjp1665j75l430', '216.73.216.244', '1752214352', '1752214352', '/shop_content.php?coID=8&XTCsid=a8f768c639dfd62c2d6d3cd7ed21b720')

[XT SQL Error]