1366 - Incorrect integer value: '' for column `pella-ware`.`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', '4dfa130ea7a13814c9dee1854d2ad950', '3.15.156.140', '1714034965', '1714034965', '/newsletter.php?language=de')

[XT SQL Error]