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', 'bd928ajlgrj94d7fjev4l5eqd4', '3.226.251.81', '1566653674', '1566653674', '/shop/index.php')

[XT SQL Error]