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', '4m0ctslqnlt6h9g0j5eekdqo51', '216.73.216.60', '1760508103', '1760508103', '/index.php?XTCsid=7f3d063595fd0cf7dd24ecea4b1409d6&cat=c12_Music.html')

[XT SQL Error]