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', 'jn6q17cmbcccc423lfomp6gqq2', '216.73.216.222', '1765950472', '1765950472', '/index.php?XTCsid=3547ee950f9337e348e5e07def1466f0&cat=c4_Beer-Mugs.html')

[XT SQL Error]