string ClientconnString = @"Data Source=D:\DB\App.sdf;Encrypt Database=True;Password=@APpsn_985@;Persist Security Info=False;Max Database Size = 4091";
            SqlCeConnection conn = new SqlCeConnection(ClientconnString);
            conn.Open();

            SqlCeCommand CeCmd = conn.CreateCommand();
            CeCmd.CommandText = @"UPDATE F_finger SET updatedt=@updatedt  WHERE p_empno='AK6277'";
            CeCmd.Parameters.Add("@updatedt", SqlDbType.DateTime, 30);
            CeCmd.Parameters["@updatedt"].Value = DateTime.Now;
            int rows = CeCmd.ExecuteNonQuery();
            conn.Close();