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', '13f56392e2e761b195522450c6d21ce2', '44.208.25.215', '1711688131', '1711688131', '/shop_content.php/coID/4/content/Impressum')

[XT SQL Error]