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', '6f4o7ubc6v93flgjuvk3m45l23', '18.221.160.2', '1746769217', '1746769217', '/xtshop/index.php?cat=c5_.html')

[XT SQL Error]