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', 'ldmpl8fqs0kmf18h55hb1qn5j2', '216.73.216.174', '1762296535', '1762296535', '/xtshop/index.php?cat=c44_.html')

[XT SQL Error]