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', '0uu339clahv1hj22rs4ksbll55', '216.73.217.150', '1793029850', '1793029850', '/xtshop/shopping_cart.php')

[XT SQL Error]