thank you Kornfeld Eliyahu Peter
cecon.Open();
SqlCeCommand insert = new SqlCeCommand("UPDATE [Otazky] SET NOdp1 = @NOdp WHERE ID = @ID", cecon);
insert.Parameters.AddWithValue("@NOdp", _NOdp);
insert.Parameters.AddWithValue("@ID", _ID);
insert.ExecuteNonQuery();
MessageBox.Show("Zla odpoved ulozena!");