主题：请教，还是目录树授权问题

Dim trv1 As WinForm.TreeView = e.Form.Controls("TreeView1")
Dim trv2 As WinForm.TreeView = e.Form.Controls("TreeView2")
trv1.BuildTree("授权","分组|权限")
For Each u As UserInfo In Users
If u.Type = UserTypeEnum.User Then
If trv2.Nodes.Contains(u.Group) = False Then
trv2.Nodes.Add(u.Group)
End If
trv2.Nodes(u.Group).Nodes.Add(u.Name)
End If
Next
Trv1.Nodes(0).Expand()
trv2.ExpandAll()

我想改为，由Users生成目录树

Dim trv1 As WinForm.TreeView = e.Form.Controls("TreeView1")
Dim trv2 As WinForm.TreeView = e.Form.Controls("TreeView2")
trv1.BuildTree("授权","分组|权限","","分组 DESC")
Dim cmd As New SQLCommand
Dim dt As DataTable
cmd.C '如果用外部数据源指定数据源名称
cmd.CommandText = "SELECT * From {Users}"  ‘Users表中有Group，Roles，Name列
dt = cmd.ExecuteReader()
For Each dr As DataRow In dt.Datarows
    If dr("Group") <> "管理员" Then
       If trv2.Nodes.Contains(dr("Group")) = False Then '判断是否存在指定名称的节点.
          trv2.Nodes.Add(dr("Group")) '增加节点.如果增加成功,则返回所增加的节点
       End If
       If trv2.Nodes(dr("Group")).Contains(dr("Roles")) = False Then '判断是否存在指定名称的节点
          trv2.Nodes(dr("Group")).Add(dr("Roles"))
       End If 
          trv2.Nodes(dr("Group")).Nodes(dr("Roles")).Nodes.Add(dr("Name"))
    End If      
Next
Trv1.Nodes(0).Expand() '展开节点
trv2.ExpandAll() '展开节点及其子节点