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', 'd80ukc47aqq56g8vb9ca8m3am7', '216.73.216.110', '1752971917', '1752971917', '/index.php?cat=c6_Foodstuffs.html&XTCsid=a0c8d0b3d08cb472c84559a313755d47')

[XT SQL Error]