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', 'p8ifc2nc35l2v2os6o7kc0p066', '216.73.216.141', '1751427784', '1751427784', '/index.php?XTCsid=daa6f8b0b1627359e5b4395c810c3f25')

[XT SQL Error]