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', '5hev5ckfqktatku4bp8j3lt007', '216.73.216.63', '1774272143', '1774272143', '/index.php?XTCsid=1d5dd97ce421ec9dee05990fab78bd20')

[XT SQL Error]