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', 'e22a088054ffd6d47f0e661bdf4453bd', '216.73.216.190', '1776277465', '1776277465', '/shop/product_info.php?info=p90_.html')

[XT SQL Error]