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', '0lmrnkulnt2k95nv5503m87p36', '3.142.221.103', '1746767379', '1746767379', '/xtshop/product_info.php?info=p1120_.html')

[XT SQL Error]