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', 'qs5tjqmnho3fh5cbioo39ch7m3', '107.22.127.78', '1493220974', '1493220974', '/product_info.php?info=p692_Suppenschuessel--Dino-s-Ursuppe----Nudeln.html&refID=nlrss')

[XT SQL Error]