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', 'ac1ujaon9c2hab0qqi4fa2cev7', '216.73.216.147', '1751965651', '1751965651', '/index.php?XTCsid=880b267136b28fa870157304bf093b31')

[XT SQL Error]