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', '7funpadjrn0ksag84cpt55mps1', '216.73.216.60', '1760508749', '1760508749', '/shop_content.php?XTCsid=e65207aee44f142683bacdd3544c84a8&coID=4')

[XT SQL Error]