Question

我有一个带有两个文本框的计算器，用户在每个文本框中输入一个数字。然后，他们单击加号，减号，除法或乘法按钮，它会对数字执行此功能。这些数字将保存到名为listbox1的列表框中。当用户单击以显示结果时，将使用所有已保存的值填充列表框，并且应用程序是SUPPOSED以将列表框项目保存到访问数据库。它不起作用。下面是我的代码，其中numFirst是数据库表中类别的名称：

Private Sub btnDisplay_Click(sender As Object, e As EventArgs) Handles 
  btnDisplay.Click
    ListBox1.Items.Clear()

    For arrayindex As Integer = 0 To intarrayCount - 1

        ListBox1.Items.Add(Input(arrayindex))
        ListBox1.Text = Convert.ToString(ListBox1.Items.Item(arrayindex))

    Next arrayindex

    Dim query As String = "SELECT * FROM wk6"
    Dim connectionString As String = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=C:\Users\helse_000\Desktop\APU\VB Advanced\week4\ENTD461_wk4_Andrew_Helsel\ENTD461_wk2_Andrew_Helsel\calculator.mdb"
    Dim command As OleDbCommand = New OleDbCommand
    Dim var1 As String = Convert.ToString(ListBox1.Items.Item(0))
    command.CommandText = "INSERT into wk6 (numFirst) VALUES (" + var1 + ")"

Answer 1

想出来，删除了select all查询字符串，并在修改结果后将我的文本框字段变为参数，以适应表格所需的格式。

For i As Integer = 0 To ListBox1.Items.Count - 1
        Dim firstString As String = Convert.ToString(ListBox1.Items.Item(i))
        Dim leftPart As String = firstString.Split(Convert.ToChar     
(strButtonSelected))(0)
        Dim rightPart As String = firstString.Split(Convert.ToChar("="))(1)
        Dim a As Integer = firstString.IndexOf(strButtonSelected)
        Dim b As Integer = firstString.IndexOf("=")
        Dim secNum = firstString.Substring(a + 1, b - 4)
        secNum = secNum.Trim

Dim conn As OleDbConnection = New OleDbConnection("Provider=Microsoft.Jet.OLEDB.4.0;
Data Source=C:\Users\helse_000\Desktop\APU\VB Advanced\week4\ENTD461_wk4_Andrew_Helsel\ENTD461_wk2_Andrew_Helsel\calculator.mdb")

        Dim command As OleDbCommand = New OleDbCommand
        Dim cmdstring As String = "INSERT INTO wk6 (numFirst, numSecond, Operator, equals, Answer)" + " VALUES (@firstName,@lastName,@Operator,@equals,@answer)"

        command = New OleDbCommand(cmdstring, conn)
        command.Parameters.AddWithValue("@firstName", leftPart)
        command.Parameters.AddWithValue("@lastName", secNum)
        command.Parameters.AddWithValue("@Operator", strButtonSelected)
        command.Parameters.AddWithValue("@equals", "=")
        command.Parameters.AddWithValue("@answer", rightPart)
        conn.Open()

        command.ExecuteNonQuery()

        conn.Close()

添加列表框值以访问数据库窗口表单应用程序

1 个答案: