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', 'du5m9at5cru84sp42tu5qe7t80', '216.73.216.113', '1775192126', '1775192126', '/index.php?XTCsid=14a7d2371c686363b43a803ce20bf936')

[XT SQL Error]