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', 'qm39locleur9tak0dto57e8jc5', '216.73.216.110', '1752972063', '1752972063', '/products_new.php?XTCsid=72205775904d1a5c41b590dd7b5ff1d6')

[XT SQL Error]