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', '95lj63trcc9h877e4hb7didpv5', '216.73.216.9', '1758223029', '1758223029', '/index.php?XTCsid=daa6f8b0b1627359e5b4395c810c3f25')

[XT SQL Error]