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', 'h0m201grjfj95sg2rqq41j51o7', '216.73.216.63', '1774334136', '1774334136', '/index.php?XTCsid=d69323e512039a0cb17dc3c523f9394c')

[XT SQL Error]