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', '5gv6nra91vtgdi8vk9u18f2195', '216.73.216.63', '1773831591', '1773831591', '/product_info.php?XTCsid=e65207aee44f142683bacdd3544c84a8&info=p14_65-drinking-cups-1-2-Liter.html')

[XT SQL Error]