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', '8272b82fceda6edfa2e2407a52dfd37a', '216.73.216.190', '1776276387', '1776276387', '/shop/product_info.php?info=p95_.html')

[XT SQL Error]