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', 'arh7tsd7bkc4s0j0p30a84b316', '216.73.216.9', '1758140803', '1758140803', '/index.php?XTCsid=9265b55633a2cb4e8ed6db3536c73ca5&cat=c5_Crockery.html')

[XT SQL Error]