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', '4o9srdmnmmgigtruu8k01uff46', '34.204.202.44', '1586466685', '1586466685', '/Produkte/Mathematik/Blankokartei-fuer-Mathematik-mit-Kaestchen::2220.html', 'Keiner/None')

[XT SQL Error]