问题描述
我的下面的代码无效,它产生此错误"对象引用未设置为对象的实例。"它应该做的是从我的数据表中检索值并填充我的列表视图。任何想法有什么问题?
My code below is not working, its producing this error "Object reference not set to an instance of an object." What it should do is retrieve values from my datatable and populate my listview. Any ideas what is wrong?
Sub fetch_DATABASE(ByVal getclass As String)
'load database into datatable into listview
Dim loadThisClass As String
loadThisclass = getclass
'load class data from MS access db
Dim cnn As New OleDb.OleDbConnection
Dim cmd As New OleDb.OleDbCommand
Dim dataAdapter As New OleDb.OleDbDataAdapter
cnn.ConnectionString = "Provider=Microsoft.ACE.OLEDB.12.0;Data Source=QuizDB.accdb"
cnn.Open()
With cmd
.Connection = cnn
.CommandText = "SELECT * FROM " & loadThisClass
End With
'create datatable
Dim MyDataTable As New DataTable
dataAdapter.SelectCommand = cmd
'use dataAdapter values to fill the DataTable
dataAdapter.Fill(MyDataTable)
'loop through each row of the datatable and add to ListItem
Dim MyDataRow As DataRow
For i = 0 To MyDataTable.Rows.Count
MyDataRow = MyDataTable.Rows(i)
LVITEMS.SubItems.Add(MyDataRow("UserName").ToString())
LVITEMS.SubItems.Add(MyDataRow("Score1").ToString())
LVITEMS.SubItems.Add(MyDataRow("Score2").ToString())
LVITEMS.SubItems.Add(MyDataRow("Score3").ToString())
LVITEMS.SubItems.Add(MyDataRow("AverageScore").ToString())
Next i
'display in listview
User_listView.Items.Add(LVITEMS)
End Sub
推荐答案
此论坛讨论并询问有关Visual Studio中的测试工具的问题,包括Web性能,负载测试和编码的UI测试。
This forum is discuss and ask questions about the Test tools in Visual Studio including web performance, load testing and Coded UI testing.
由于您的问题与WinForm开发更相关,我将帮助您将此线程移至Windows窗体论坛以获得更好的帮助。
Since your problem is more related to WinForm development, I will help you move this thread to Windows Forms forum for a better help.
最诚挚的问候,
Weiwei
Best Regards,
Weiwei
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