vb.net 从 SQL Server 数据库填充 TreeView
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Populate TreeView from SQL Server database
提问by SellaKumar
I want to populate a TreeView from SQL database.
我想从 SQL 数据库填充 TreeView。
I have a table with NODE_NAME AND PARENT_NODE columns and the child nodes should b created based on the PARENT_NODE.
我有一个包含 NODE_NAME AND PARENT_NODE 列的表，子节点应该基于 PARENT_NODE 创建。
How can I do this in vb.net?
我怎样才能在 vb.net 中做到这一点？
回答by LarsTech
With your DataTable, you can try this method below. If it doesn't find the parent node, it adds it. The "Find" function returns an array of nodes, but in this case, it's assumed none or one node is always found:
使用您的数据表，您可以在下面尝试此方法。如果它没有找到父节点，它会添加它。"Find" 函数返回一个节点数组，但在这种情况下，假设始终找不到节点或一个节点：
Private Sub AddNode(parentNode As String, nodeText As String)
Dim node As New List(Of TreeNode)
node.AddRange(TreeView1.Nodes.Find(parentNode, True))
If Not node.Any Then
node.Add(TreeView1.Nodes.Add(parentNode, parentNode))
End If
node(0).Nodes.Add(nodeText, nodeText)
End Sub
You would use it by enumerating through the rows in your DataTable:
您可以通过枚举 DataTable 中的行来使用它：
For Each dr As DataRow In dt.Rows
AddNode(dr("ParentNode").ToString, dr("NodeName").ToString)
Next
TreeView1.ExpandAll()
