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', 'g7rd67hnhbjlje4l3u5m0853i6', '216.73.216.197', '1751514690', '1751514690', '/index.php?XTCsid=8045f38f0bef4724ff52869f85afd31c')

[XT SQL Error]