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', 'fugfmuhlub7hr57scnufdu7is6', '216.73.216.80', '1751323401', '1751323401', '/index.php?cat=c8_Disposable-tableware.html&XTCsid=cdb5ff3e66355dfdab8c76076c4013e1')

[XT SQL Error]