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', '1dl23evn7huj4bkn0qtent0q66', '3.85.92.139', '1561471171', '1561471171', '/shop_content.php/coID/2/content/Widerrufs-Belehrung')

[XT SQL Error]