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', '86njeud7erm7qhjra9hr05k431', '18.219.81.99', '1746976469', '1746976469', '/xtshop/product_info.php?info=p997_.html')

[XT SQL Error]