Question

我在解决这个问题时遇到了问题。

如果您运行嵌入在下面的代码中的查询，它会显示要求的总问题（TotalQuestions），Total Correct（TotalCorrect2）和正确的百分比（PercentCorrect2）。

我们有学生参加视频教程。

每节课后，他们会接受测验，总共有30个问题。

要通过教程的每个部分，学生必须至少获得80％的测验成绩。

以下代码计算总问题，总正确率和正确百分比。

这是我遇到问题的地方。

如果学生回答了所有30个问题并且80％或更多的问题是正确的，那么学生就可以获得证书，这样他/她就可以打印出他或她的证书。

如果不符合这两个标准，证书将对学生隐藏。

我对此任务的IF部分有困难。

例如，

if totalQuestions = 30 and percentCorrect2 >= 80 then

  btnGetUser.Visible = True

else

 btnGetUser.Visible = False

end if

This above is not working.

当我运行代码，并且特定用户满足IF语句的条件时，应该公开证书。当我在SSMS中运行时，它会这样做。

到目前为止，证书仍然隐藏，即使我正在测试已经通过测试并已经完成测试的用户。

当我调试代码时，我可以看到totalQuestions显示30这是正确的但其余显示为0.

任何想法我可能做错了什么？

Dim s As String = ";WITH Questions AS " & _
       " ( SELECT SQ.QuestionID, " & _
         "   CorrectChoices = COUNT(NULLIF(SC.IsCorrect, 0)), " & _
        "    ChoicesGiven = COUNT(SA.ChoiceID), " & _
       "     CorrectChoicesGiven = COUNT(CASE WHEN SA.ChoiceID IS NOT NULL AND SC.IsCorrect = 1 THEN 1 END), " & _
       "     ExtraChoicesGiven = CASE WHEN COUNT(SA.ChoiceID) > COUNT(NULLIF(SC.IsCorrect, 0)) THEN COUNT(SA.ChoiceID) - COUNT(NULLIF(SC.IsCorrect, 0)) ELSE 0 END " & _
        "  FROM SurveyQuestions SQ " & _
        "  INNER JOIN SurveyChoices SC " & _
        "  ON SQ.QuestionId = SC.QuestionID " & _
        "  LEFT JOIN SurveyAnswers SA " & _ 
        "  ON SA.QuestionId = SC.QuestionID  " & _
        "  AND SA.ChoiceID = SC.ChoiceID " & _
        "  AND SA.UserName = @username " & _
        "  GROUP BY SQ.QuestionID " & _
        " ), QuestionScores AS " & _
        "   (SELECT QuestionID, " & _
        "     Score = CASE WHEN CorrectChoicesGiven - ExtraChoicesGiven < 0 THEN 0 " & _
        "             ELSE CAST(CorrectChoicesGiven - ExtraChoicesGiven AS FLOAT) / CorrectChoices " & _
        "             END, " & _
        "     Score2 = ISNULL(CAST(CorrectChoicesGiven AS FLOAT) / NULLIF(CASE WHEN ChoicesGiven > CorrectChoices THEN ChoicesGiven ELSE CorrectChoices END, 0), 0) " & _
        "    FROM Questions " & _
        "   )
         "   SELECT TotalQuestions = COUNT(*), " & _
         "    TotalCorrect = SUM(Score), " & _
         "    PercentCorrect = CAST(100.0 * SUM(Score) / COUNT(*) AS DECIMAL(5, 2)), " & _
         "    TotalCorrect2 = SUM(Score2), " & _
          "   PercentCorrect2 = CAST(100.0 * SUM(Score2) / COUNT(*) AS DECIMAL(5, 2)) " & _
          "  FROM QuestionScores;"

Dim connStr As String = ConfigurationManager.ConnectionStrings("DBConnectionString").ConnectionString
Dim conn As New SqlConnection(connStr)
Dim cmd As New SqlCommand(s, conn)

Dim TotalQuestions As Integer
Dim TotalCorrect As Double
Dim TotalPercent As Decimal
Dim TotalCorrect2 As Double
Dim TotalPercent2 As Decimal

conn.Open()
cmd.Parameters.AddWithValue("@username", username.Text)
Dim reader As SqlDataReader = cmd.ExecuteReader()

If reader.Read() Then
    TotalQuestions = reader.GetInt32(0)
    TotalCorrect = reader.GetDouble(1)
    TotalPercent = reader.GetDecimal(2)
    TotalCorrect2 = reader.GetDouble(3)
    TotalPercent2 = reader.GetDecimal(4)
End If
reader.Close()
conn.Close()
If TotalQuestions = 30 and TotalPercent2 >= 80 Then
    btnGetUser.Visible = True
Else
    btnGetUser.Visible = False
End If

用户达到目标后，使用户可以看到证书

0 个答案: