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', 'gvnfhknt8qogo74438glq6rqk7', '216.73.216.180', '1766283940', '1766283940', '/shop_content.php?XTCsid=85f438a686cbfb5e3ea5e5d6b9611958&coID=2')

[XT SQL Error]