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', 'v8fi32srev5kmi6uladloosih5', '216.73.216.60', '1760540915', '1760540915', '/shop_content.php?XTCsid=80c3e9fc87b53cb0d288d19ef4e9b63c&coID=4')

[XT SQL Error]