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', 'em8vebcmgtlvgu5q6guvkgd8n2', '216.73.216.113', '1775614833', '1775614833', '/shop_content.php?XTCsid=3547ee950f9337e348e5e07def1466f0&coID=8')

[XT SQL Error]