比较 "if" 构造中的值时出错

Question

我正在做一个人脸识别项目，我想将x.label返回值与保存到数据库中的ID进行比较。我总是在 if 条件下将 ID 与 x.label

进行比较时出错

  public int Predict(Image<Gray, Byte> testImage)
        {

            Emgu.CV.FaceRecognizer.PredictionResult x;
            if (testImage != null)
            {
                x= fr.Predict(testImage);
                pictureBox1.Image = testImage.ToBitmap();
                //MessageBox.Show(x.Label.ToString()+" "+x.Distance.ToString());

                OleDbCommand D1 = new OleDbCommand("Select [ID] FROM [connect]", DBConnection);
                OleDbDataReader reader = D1.ExecuteReader();
                while (reader.Read())
                {

                   if (Convert.ToInt32(reader["ID"]) == x.Label)
                   {

                       OleDbCommand insert1 = new OleDbCommand("UPDATE OutputReport SET [Attendance]='yes' WHERE [StudentID]='109';", DBConnection);
                       insert1.ExecuteNonQuery();
                        MessageBox.Show(" its working");
                    }
               }
                RefreshDBConnection();


                if (x.Distance < 69)
                    return x.Label;
                else
                    MessageBox.Show("Error!!, The detected Face is neither recognised nor enrolled");
                return -1;
            }

            else

            {

                return -1;
            }

        }

Answer 1

如果我的理解是正确的，您需要检查 x.Label 值与 MS-Access 数据库中的 ID 列值。为此，您需要执行 reader 并分配值。

   public int Predict(Image<Gray, Byte> testImage)
        {

            Emgu.CV.FaceRecognizer.PredictionResult x;
            if (testImage != null)
            {
                x= fr.Predict(testImage);
                pictureBox1.Image = testImage.ToBitmap();
                //MessageBox.Show(x.Label.ToString()+" "+x.Distance.ToString());

                OleDbCommand D1 = new OleDbCommand("Select [ID] FROM [connect]", DBConnection);
                OleDbDataReader reader = D1.ExecuteReader();
                while (reader.Read())
                {

                   if (Convert.ToInt32(reader["ID"]) == x.Label)
                   {

                       OleDbCommand insert1 = new OleDbCommand("UPDATE OutputReport SET [Attendance]='yes' WHERE [StudentID]='109';", DBConnection);
                      int i= insert1.ExecuteNonQuery();
                      MessageBox.Show(i.ToString());
                   }
               }
                RefreshDBConnection();

                if (x.Distance < 69)
                    return x.Label;
                else
                    MessageBox.Show("Error!!, The detected Face is neither recognised nor enrolled");
                return -1;
            }

        else

        {

            return -1;
        }


    }

比较 "if" 构造中的值时出错

Error comparing values in "if" construct

c#

database

ms-access

if-statement

face-recognition