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', 'ae2d1d9ae7b3acaf01682fea5056414e', '216.73.216.169', '1755543571', '1755543571', '/shop/product_info.php?info=p4_.html')

[XT SQL Error]