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', 'd8c8a0b49ffc79dcfa53e8efc56fc64b', '3.144.100.38', '1722086205', '1722086205', '/shop_content.php/coID/2/content/Datenschutz')

[XT SQL Error]