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', '9a95f21cg6dgqpab1unp42g5h5', '216.73.216.9', '1758053681', '1758053681', '/index.php?XTCsid=0972f945ed25ca4859b15efb2d6da3e7')

[XT SQL Error]