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', 'hqgvl5rqt11ll6har9ng5us3f1', '216.73.217.54', '1788189460', '1788189460', '/popup_content.php?XTCsid=6c2468ca28c6c182aaed37353d32ae32&coID=1')

[XT SQL Error]