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', '31o1sfuh8eedji1ocf2083a366', '18.222.191.57', '1746876617', '1746876617', '/xtshop/product_info.php?info=p646_.html')

[XT SQL Error]