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', '3e728iifn2kp8gm00s910jm8a2', '216.73.216.9', '1758042798', '1758042798', '/index.php?XTCsid=cc9bbfbe9121132c07494a23739109f1')

[XT SQL Error]