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', '3766skovsouks8ef3ils2ihb83', '216.73.216.174', '1762243358', '1762243358', '/xtshop/index.php?cat=c24_.html')

[XT SQL Error]