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', 'dtkcm9nkiqu3f4ud8onubk9pb4', '216.73.216.63', '1774552149', '1774552149', '/products_new.php?XTCsid=d0fb6f95a363340d124d7dc76e615e44')

[XT SQL Error]