C# 还有工作…谢谢你，卡博特。。。我试过你的答案。。。这一切都适用于节点部分。。。但是我没有看到任何叶..你确定在返回数据中的叶之前父节点就在那里吗？是的。。。父节点是第一个，我得到了所有节点，如Parent1、Parent2和Parent3，但我没有看到任何

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还有工作…谢谢你，卡博特。。。我试过你的答案。。。这一切都适用于节点部分。。。但是我没有看到任何叶..你确定在返回数据中的叶之前父节点就在那里吗？是的。。。父节点是第一个，我得到了所有节点，如Parent1、Parent2和Parent3，但我没有看到任何leafsHey Cabbott。。。我让它工作了。然而，要在我的树上获取数据需要花费很长时间。它崩溃了，但它工作了。。。有没有办法解决这个问题。。。我不确定，但我想尝试使用字典可能会有所帮助？？？有点像字典…谢谢你Jonn。。。但我完全使用c#而且，我有大约500个数据和30个父节点…：）。。。我用另一种想法向您的原始问题添加了一条注释，但我这里的主要观点不是代码-这只是我测试它以确保其工作的方式-它是填充第一个（父）节点，然后使用基于父名称的Linq填充第二个。嗨，John。。。在treeNode.Nodes.Add（node1）上；“节点”上出现错误。。。它说它没有定义我至少让它运行John。。。我想你可能是指treeNode.儿童.添加（node1）；。。。然而，这需要很多时间来获取我的数据，并导致它崩溃。。。有没有更有效的方法？我目前正在尝试使用字典，但运气不好

ListA  ListB  labelName
 NY           Parent1
        NY    Leaf1
 HI           Parent2
 AK           Parent3

            SqlCommand cmd = con.CreateCommand();

            comd.CommandText = "SELECT * FROM myTable";
            con.Open();
            SqlDataReader reader = comd.ExecuteReader();
            while (reader.Read())
            {
                City MyData = new City();

                MyData.ListA = reader["ListA"].ToString().Trim();
                MyData.ListB = reader["ListB"].ToString().Trim();
                MyData.labelName = reader["labelName"].ToString().Trim();
                giveData.Add(MyData);
            }

            int count = 1;

            List<TreeNode> myNode = new List<TreeNode>();
            foreach (City MyData in giveData)
            {
                // 1st foreach
                    if (MyData.ListA != "")
                    {

                        TreeNode treeNode = new TreeNode();
                        treeNode.id = count++;
                        treeNode.name = MyData.labelName;
                        treeNode.leaf = false;

                        List<TreeNode> Level1 = new List<TreeNode>();
                        foreach (City labelName  in giveData)
                        {
                            if (labelName.ListA == labelName.ListB)
                            {// 2nd foreach
                                TreeNode node1 = new TreeNode();
                                node1.id = count++;
                                node1.name = labelName.labelName;
                                node1.leaf = true;

                                Level1.Add(node1);
                            }
                        }

                        treeNode.children = Level1;
                        myNode.Add(treeNode);
                }
            }
            return JsonConvert.SerializeObject(myNode);

var MyData = new List<City>
                  {
                     new City {ListA = "AK", ListB = "", labelName = "Alaska"},
                     new City {ListA = "HI", ListB = "", labelName = "Hawaii"},
                     new City {ListA = "", ListB = "HI", labelName = "Hawaii Leaf 1"},
                     new City {ListA = "", ListB = "HI", labelName = "Hawaii Leaf 2"},
                     new City {ListA = "NY", ListB = "", labelName = "New York"},
                     new City {ListA = "", ListB = "NY", labelName = "New York Leaf 1"},
                     new City {ListA = "", ListB = "NY", labelName = "New York Leaf 2"}
                  };

var index = 0;
var parents = (from p in MyData
               where p.ListB == ""
               select p).ToDictionary(p => p.ListA, p => new TreeNode { id = index++, name = p.labelName, leaf = false });

var leaves = (from l in MyData
              where l.ListA == ""
              group l by l.ListB into stateGroup
              select stateGroup).ToDictionary(g => g.Key, g => g.ToList());

foreach (var leaf in leaves.Where(leaf => parents.ContainsKey(leaf.Key)))
{
    parents[leaf.Key].children =
        leaf.Value.Select(l => new TreeNode {id = index++, name = l.labelName, leaf = true}).ToList();
}

var myNode = parents.Select(p => p.Value).ToList();

return JsonConvert.SerializeObject(myNode);

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
    Dim x As New List(Of City)

    x.Add(New City With {.ListA = "NY", .ListB = "", .Leaf = "Parent1"})
    x.Add(New City With {.ListA = "", .ListB = "NY", .Leaf = "Leaf1"})
    x.Add(New City With {.ListA = "HI", .ListB = "", .Leaf = "Parent2"})
    x.Add(New City With {.ListA = "AK", .ListB = "", .Leaf = "Parent3"})

    tv1.Nodes.AddRange((From y In x Where y.ListA <> "" Select New TreeNode With {
                                                                    .Name = y.ListA,
                                                                    .Text = y.Leaf}).ToArray)

    For Each nd As TreeNode In tv1.Nodes
        Dim Nm As String = nd.Name
        nd.Nodes.AddRange((From y In x Where y.ListB = Nm Select New TreeNode(y.Leaf)).ToArray)
    Next
End Sub

        int count = 1;

        List<TreeNode> myNode = new List<TreeNode>();
        foreach (City MyData in giveData)
        {
            // 1st foreach
            if (MyData.ListA != "")
            {

                TreeNode treeNode = new TreeNode();
                treeNode.id = count++;
                treeNode.name = MyData.labelName;
                treeNode.leaf = false;

                foreach (City labelName in giveData)
                {
                    if (MyData.ListA == labelName.ListB)
                    {// 2nd foreach
                        TreeNode node1 = new TreeNode();
                        node1.id = count++;
                        node1.name = labelName.labelName;
                        node1.leaf = true;

                        treeNode.Nodes.Add(node1);
                    }
                }

                myNode.Add(treeNode);
            }
        }
        return JsonConvert.SerializeObject(myNode);