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', '8goq531pq916lqthhba1vm30q1', '216.73.217.147', '1777814902', '1777814902', '/popup_content.php?XTCsid=6c2468ca28c6c182aaed37353d32ae32&coID=1')

[XT SQL Error]