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', '5ok41alko1ic5dd0qv3t9ufar6', '216.73.217.152', '1791186394', '1791186394', '/shop_content.php?XTCsid=07630e5b15e9155d8246af3ee660ca0e&coID=7')

[XT SQL Error]