1366 - Incorrect integer value: '' for column `CP_as15`.`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) values ('', 'Guest', '995a2q0i668kcsnjvcjjvb92l2', '3.15.170.2', '1738994928', '1738994928', '/index.php?XTCsid=3ea3bnp0vmbqarg8bfequsbfv5&cat=c24_Digital-Kamera-Akku.html')

[XT SQL Error]