1366 - Incorrect integer value: '' for column `hollen`.`whos_online`.`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, http_referer) values ('', 'Guest', 'u978oog79fs5pkeif5bhcr03l6', '35.172.233.215', '1597184873', '1597184873', '/Sitemap:_:8.html', 'Keiner/None')

[XT SQL Error]