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', 'j9473if9jh87sn4jl890smdhs4', '3.235.172.213', '1591133724', '1591133724', '/Sitemap:_:8.html', 'Keiner/None')

[XT SQL Error]