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', '5rlsiui69bc065udadkq1mh9j2', '216.73.216.63', '1773775183', '1773775183', '/index.php?XTCsid=1a719986c059fb57d0cc5ade098128f1')

[XT SQL Error]