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', 'c1j3dc112i3k49efs28oqvat14', '216.73.216.180', '1766206059', '1766206059', '/products_new.php?XTCsid=3dfedf8e10ab51b65faa7b7d7332d93a&language=en')

[XT SQL Error]