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', 'bd71fb3dabe8a8cb0f0319ae51ed8157', '3.238.72.180', '1669816768', '1669816768', '/shop/index.php')

[XT SQL Error]