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', '0j4mg5gf7in9m8o3k7tfodrng2', '18.97.9.168', '1742458251', '1742458251', '/xtshop/index.php?cat=c70_.html')

[XT SQL Error]