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', '393p1fe9h54itak64bi1kid3i0', '216.73.216.9', '1758167216', '1758167216', '/index.php?XTCsid=386280b5dd71f86a1e8fe3bdbe25c551&cat=c13_Accessoires.html')

[XT SQL Error]