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', 'c0cfbc0ec7a695fc2aef4b228babd9a4', '216.73.216.190', '1776281067', '1776281067', '/shop/index.php?cat=c26_.html')

[XT SQL Error]