1366 - Incorrect integer value: '' for column `agentur`.`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', '2sahje13sns8n999cstg6gk3l3', '3.235.101.50', '1601424404', '1601424404', '/index.php?cat=c37_Nacht-der-Legenden-2012.html&XTCsid=ib6sbj9jrs0n6ls84ctf015q06')

[XT SQL Error]