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', 'uht8l1mlkhm2jroshcu7a2vmf1', '216.73.216.9', '1757965936', '1757965936', '/index.php?XTCsid=ec445a26a1be1b54e711876da9fff244&cat=c2_Dekoration.html')

[XT SQL Error]