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', '5eqoug24jdgsif8ult57880md1', '216.73.216.9', '1757830053', '1757830053', '/index.php?XTCsid=935b3fdff77aef65cd9fe37ae67353da')

[XT SQL Error]