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', '25od8c7k82a9crcje4qap0t661', '216.73.216.80', '1769934783', '1769934783', '/xtshop/shop_content.php?coID=3')

[XT SQL Error]