如果填充了四个文本框，则计算和更新值VB.net

Question

如果要填充四个文本框，我想计算和更新数据库。

如果填充了1或2或3，它将不会计算，只会更新到数据库。

这是我的代码。

 Dim constring As String = "Provider=Microsoft.JET.OLEDB.4.0;Data Source=|DataDirectory|\SLACdb.mdb;"
    Dim con As OleDbConnection = New OleDbConnection(constring)
    Dim cmd As OleDbCommand
    Dim dt As DataTable = New DataTable()

    Dim prelim, midterm, prefinal, final, ave, eq As String

    prelim = txtboxprelim.Text
    midterm = txtboxmidterm.Text
    prefinal = txtboxsemi.Text
    final = txtboxfinals.Text
    ave = txtboxave.Text
    eq = txtboxequivalent.Text

    Dim sql As String = "UPDATE StudentLoad SET prelim = ?, midterm = ?, semifinals = ?, finals = ?" & _
                        " WHERE  name = '" & txtboxname.Text & "' "

    If prelim = "" Or midterm = "" Or prefinal = "" Or final = "" Then
        cmd = New OleDbCommand(sql, con)


        cmd.Parameters.AddWithValue("@p1", prelim)
        cmd.Parameters.AddWithValue("@p2", midterm)
        cmd.Parameters.AddWithValue("@p3", prefinal)
        cmd.Parameters.AddWithValue("@p4", final)

        Try
            con.Open()
            If (cmd.ExecuteNonQuery > 0) Then

            End If
            con.Close()

        Catch ex As Exception
            MsgBox(ex.Message)
        End Try
        Me.StudentRemarksTableAdapter.Fill(Me.SLACdbDataSet.StudentRemarks)
    Else
        txtboxave.Text = (prelim + midterm + prefinal + final) / 4
        If txtboxave.Text <= 77 Then
            txtboxequivalent.Text = 3
        ElseIf txtboxave.Text <= 80 Then
            txtboxequivalent.Text = 2.75
        ElseIf txtboxave.Text <= 83 Then
            txtboxequivalent.Text = 2.5
        ElseIf txtboxave.Text <= 86 Then
            txtboxequivalent.Text = 2.25
        ElseIf txtboxave.Text <= 89 Then
            txtboxequivalent.Text = 2
        ElseIf txtboxave.Text <= 92 Then
            txtboxequivalent.Text = 1.75
        ElseIf txtboxave.Text <= 95 Then
            txtboxequivalent.Text = 1.5
        ElseIf txtboxave.Text <= 98 Then
            txtboxequivalent.Text = 1.25
        ElseIf txtboxave.Text <= 100 Then
            txtboxequivalent.Text = 1
        Else
            txtboxequivalent.Text = 5
        End If

        Dim constring1 As String = "Provider=Microsoft.JET.OLEDB.4.0;Data Source=|DataDirectory|\SLACdb.mdb;"
        Dim con1 As OleDbConnection = New OleDbConnection(constring1)
        Dim cmd1 As OleDbCommand
        Dim dt1 As DataTable = New DataTable()


        Dim sql1 As String = "UPDATE StudentLoad SET prelim = ?, midterm = ?, semifinals = ?, finals = ?, average = ?, equivalent = ?" & _
                        " WHERE  name = '" & txtboxname.Text & "'"
        cmd1 = New OleDbCommand(sql1, con1)


        cmd1.Parameters.AddWithValue("@p1", prelim)
        cmd1.Parameters.AddWithValue("@p2", midterm)
        cmd1.Parameters.AddWithValue("@p3", prefinal)
        cmd1.Parameters.AddWithValue("@p4", final)
        cmd1.Parameters.AddWithValue("@p5", ave)
        cmd1.Parameters.AddWithValue("@p6", eq)


        Try
            con1.Open()
            If (cmd1.ExecuteNonQuery > 0) Then

            End If
            con1.Close()

        Catch ex As Exception
            MsgBox(ex.Message)
        End Try
    End If
    Me.StudentRemarksTableAdapter.Fill(Me.SLACdbDataSet.StudentRemarks)
    Admin.StudentLoadTableAdapter.Update(SLACdbDataSet.StudentLoad)

使用此代码，只有在填充了四个不计算的文本框后，它才会更新数据库。

对不起，英语不好

Answer 1

您的代码中的问题是prelim，中期，prefinal，final，ave和eq是字符串。

为了计算平均值，您需要将这些变量设置为整数。 因此，将Dim prelim as integer = convert.toint32(txtboxprelim.text)并将其应用于期中，预决赛，最终，ave和等式。 您的cmd.parameters应该是

cmd.Parameters.AddWithValue("@p1", txtboxprelims.text)
cmd.Parameters.AddWithValue("@p2", txtboxmidterm.text)
cmd.Parameters.AddWithValue("@p3", txtboxprefinal.text)
cmd.Parameters.AddWithValue("@p4", txtboxfinal.text)

在下面的else语句中：

txtboxave.Text = (prelim + midterm + prefinal + final) / 4

应该

ave = (prelim + midterm + prefinal + final) / 4

将您的txtboxave.text替换为ave，然后在if和else语句下面添加：

txtboxequivalent.text = eq
txtboxave.text = ave

最后，您的cmd.paremeters应该是：

cmd1.Parameters.AddWithValue("@p1", prelim.tostring)
cmd1.Parameters.AddWithValue("@p2", midterm.tostring)
cmd1.Parameters.AddWithValue("@p3", prefinal.tostring)
cmd1.Parameters.AddWithValue("@p4", final.tostring)
cmd1.Parameters.AddWithValue("@p5", ave.tostring)
cmd1.Parameters.AddWithValue("@p6", eq.tostring)