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', '8253641685659a2076d979ecb09ab695', '216.73.216.190', '1776281061', '1776281061', '/shop/product_info.php?info=p23_.html')

[XT SQL Error]