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', '467d91rrof16p56udthi8ofu85', '216.73.216.9', '1758099006', '1758099006', '/index.php?XTCsid=adc8c520bddaa9e02a40df1e2a90f128&cat=c6_Foodstuffs.html')

[XT SQL Error]