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', 'a9lji2kto3935t95l9qu0iohk1', '35.172.233.215', '1597186134', '1597186134', '/Produkte/Materialien/Der-Kleine-Karteikasten-aus-Wellpappe::2199.html', 'Keiner/None')

[XT SQL Error]