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', 'a6a7vm3f31r91h7cn0ipalqiv2', '3.128.226.211', '1746769679', '1746769679', '/xtshop/index.php?cat=c85_.html')

[XT SQL Error]