ds.tables（0）='ds.tables（0）'拋出類型'System.NullReferenceException'的異常vb.net

Question

我試圖從一個按鈕單擊事件中的2個不同的表中拉數據。我檢查了一切，似乎沒有任何錯字或任何東西，但不斷收到此錯誤。

下面是我的按鈕單擊事件

Protected Sub btnFindRepair_Click(sender As Object, e As EventArgs) Handles btnFindRepair.Click 

    Dim connection As New SqlConnection("Data Source=(LocalDB)\MSSQLLocalDB;AttachDbFilename=|DataDirectory|\ITrepair.mdf;Integrated Security=True") 

    Dim command As New SqlCommand("SELECT * from Repair; SELECT * FROM Customer WHERE Tracking_Number = @Tracking_Number", connection) 

    command.Parameters.Add("@Tracking_Number", SqlDbType.Int).Value = txtTrackingNumber.Text 

    Dim adapter As New SqlDataAdapter(command) 
    Dim ds As System.Data.DataSet 
    Dim table As New DataTable() 

    adapter.Fill(table) 


    'Repair Details 
    DDLBookedInBy.SelectedItem.Text = "" 
    DDLDeviceType.SelectedItem.Text = "" 
    txtBookedInDate.Text = "" 
    txtDeviceName.Text = "" 
    DDLAccessories.SelectedItem.Text = "" 
    txtDevicePassword.Text = "" 
    DDLRepairType.Text = "" 
    txtTechnical.Text = "" 
    txtCompletedNotes.Text = "" 
    DDLRepairStatus.Text = "" 

    'Customer Details 

    txtFname.Text = "" 
    txtLname.Text = "" 
    txtContactNum.Text = "" 
    txtAltContactNum.Text = "" 
    txtAddress.Text = "" 


    If table.Rows.Count() > 0 Then 

     ' return only 1 row 
     DDLBookedInBy.SelectedItem.Text = ds.tables(0).Rows(0)(2).ToString() 
     DDLDeviceType.SelectedItem.Text = ds.tables(0).Rows(0)(3).ToString() 
     txtBookedInDate.Text = ds.tables(0).Rows(0)(4).ToString() 
     txtDeviceName.Text = ds.tables(0).Rows(0)(5).ToString() 
     DDLAccessories.SelectedItem.Text = ds.tables(0).Rows(0)(6).ToString() 
     txtDevicePassword.Text = ds.tables(0).Rows(0)(7).ToString() 
     DDLRepairType.Text = ds.tables(0).Rows(0)(8).ToString() 
     txtTechnical.Text = ds.tables(0).Rows(0)(9).ToString() 
     txtCompletedNotes.Text = ds.tables(0).Rows(0)(10).ToString() 

     txtFname.Text = ds.tables(1).Rows(1)(4).ToString() 
     txtLname.Text = table.Rows(1)(5).ToString() 
     txtContactNum.Text = table.Rows(1)(6).ToString() 
     txtAltContactNum.Text = table.Rows(1)(7).ToString() 
     txtAddress.Text = table.Rows(1)(8).ToString() 

    Else 
     MsgBox("NO DATA found") 
    End If 




End Sub 

Answer 1

與table替換的ds.tables(0)所有出現的代碼。您尚未初始化DataSet ds，但您不需要它，因爲您將DataTable tbl填入adapter.Fill(table)。

例如：

If table.Rows.Count > 0 Then 
    DDLBookedInBy.SelectedItem.Text = table.Rows(0)(2).ToString() 
    ' .... ' 

如果你想填補DataSet使用：

Dim ds As System.Data.DataSet 
Dim table As New DataTable() 

ds = New DataSet() 
adapter.Fill(ds) 


If table.Rows.Count > 0 Then 
    DDLBookedInBy.SelectedItem.Text = ds.Tables(0).Rows(0)(2).ToString() 
    ' .... ' 
    txtFname.Text = ds.Tables(1).Rows(1)(4).ToString() 
    ' ... '