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', 'hb784lvicg09uq14mgd81vme21', '216.73.216.131', '1763735867', '1763735867', '/index.php?XTCsid=daa6f8b0b1627359e5b4395c810c3f25')

[XT SQL Error]