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', '5qcjd0fa0pb56uorvcdsbea5j4', '216.73.216.197', '1751514137', '1751514137', '/index.php?XTCsid=d61f6f679fc365839a400c6959a2cb6e')

[XT SQL Error]