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', '73md8hkk1e2gvf40smeur1pqj0', '216.73.216.112', '1763848786', '1763848786', '/index.php?XTCsid=903d490a11e72fb45b2507d2f3478040&cat=c9_Tabledeko.html')

[XT SQL Error]