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', 's56d5d3e5to9c1snh0eho6agk0', '216.73.216.9', '1758151674', '1758151674', '/index.php?XTCsid=e32f172c0b23edb48fc4fb80463cba38')

[XT SQL Error]