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Editorial Team
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Asked: 2026-05-26T05:33:59+00:00

Consider the following table. It has 3 filed with the following data. Now I

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Consider the following table. It has 3 filed with the following data. Now I want to show the data in TreeView Control in asp.net and c#
I will select all the data in a DataTable. 

category_id category_name   parents_id
1           Root            NULL
2           Teacher         1
3           Student         1
4           TeacherA        2
5           TeacherB        2
6           TeacherC        2
7           StudentA        3
8           StudentB        3
9           StudentC        3
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1 Answer

  1. Editorial Team

    Here are some useful tips for you: for implementing tree view using asp.net and c#

    NOte: I did not implement and did not use your datatable data here ….

    • TreeView control expects a heirarchical data structure, so we cant
      bind the DataTable to menu directly.

    • Use data table Select where ParentID = ID

    • Please use a recursive method to create child items relevent to
      current menu item ID

    • Here is an working example that you may use to transfer your
      ralational data structure (TABLE) to hierarchical data
      structure (TREE) using the relationship between ParentID and ID

      <%@ Page Language="C#" %>
<html xmlns="http://www.w3.org/1999/xhtml">
 <head id="Head1" runat="server">
   <script runat="server">

protected override void OnLoad(EventArgs e)
{
    base.OnLoad(e);
    if (!this.IsPostBack)
        this.AddNodes(this.trvCategories.Nodes, 0, this.LoadData());
}
private void AddNodes(TreeNodeCollection nodes, int level, System.Data.DataTable dt)
{
    string filterExp = string.Format("ParentID='{0}'", level);
    foreach (System.Data.DataRow r in dt.Select(filterExp))
    {
        TreeNode item = new TreeNode()
        {
            Text = r[1].ToString(),
            Value = r[2].ToString()
        };
        this.AddNodes(item.ChildNodes, int.Parse(r[0].ToString()), dt);
        nodes.Add(item);
    }
}
private System.Data.DataTable LoadData()
{
    ///
    /// For the simplicity I do build the datatable dynamically,
    /// But you may get this data from the DATABASE
    ///
    System.Data.DataTable dt = new System.Data.DataTable();
    dt.Columns.Add("ID", String.Empty.GetType());
    dt.Columns.Add("[Name]", String.Empty.GetType());
    dt.Columns.Add("[Value]", String.Empty.GetType());
    dt.Columns.Add("ParentID", String.Empty.GetType());
    dt.Columns.Add("[Order]", String.Empty.GetType());
    int index = 9;
    for (int i = 0; i < 1100; i++)
    {
        string item = "{0},Item{1},Value{1},{2},{1}";
        if (i < 110)
        {
            index = i < 10 ? 0 : int.Parse(Math.Ceiling((decimal)i / 10).ToString());
            dt.Rows.Add((string.Format(item, i + 1, i, index)).Split(char.Parse(",")));
        }
        else
        {
            if (i % 10 == 0) index++;
            dt.Rows.Add((string.Format(item, i + 1, i, index)).Split(char.Parse(",")));
        }
    }
    return dt;
}

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