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', 'frptd72i390vg7kl9eea2ntvq2', '216.73.216.147', '1751958886', '1751958886', '/popup_content.php?coID=1&XTCsid=ec445a26a1be1b54e711876da9fff244')

[XT SQL Error]