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', 'lh7evil59sj089vnsrul6o99r3', '216.73.216.127', '1752881789', '1752881789', '/index.php?cat=c8_Disposable-tableware.html&XTCsid=e65207aee44f142683bacdd3544c84a8')

[XT SQL Error]