Populate TreeView from DataBase

Question

I have a database table (named Topics) which includes these fields :

1. topicId
2. name
3. parentId

and by using them I wanna populate

Answer 1

This code runs perfectly for me. Thought it might be useful for somebody looking to display hierarchial data in a treeview.By far, i guess this is the simplest. Please check it out and upvote if it helps you.

Reference : https://techbrij.com/display-hierarchical-data-with-treeview-in-asp-net

C# code:

 //dtTree  should be accessible in both page load and AddNodes()
    //DocsMenu is the treeview Id
          DataTable dtTree = new DataTable(); 
//declare your connection string
                protected void Page_Load(object sender, EventArgs e)
                {
                    //DataTable dtTree = new DataTable();
                    using (con)
                    {
                        con.Open();

                        string sQuery = "Select topicId,parentid,name from tbl_topicMaster";
                        SqlCommand cmd = new SqlCommand(sQuery, con);
                        cmd.CommandType = CommandType.Text;
                        SqlDataAdapter da = new SqlDataAdapter(cmd);
                        da.Fill(dtTree);
                        da.Dispose();
                        con.Close();
                    }

                    AddNodes(-1, DocsMenu.Nodes);
                }




                void AddNodes(int id, TreeNodeCollection tn)
                {
                    foreach (DataRow dr in dtTree.Select("parentid= " + id))
                    {
                        TreeNode sub = new TreeNode(dr["name"].ToString(), dr["topicId"].ToString());
                        tn.Add(sub);
                        AddNodes(Convert.ToInt32(sub.Value), sub.ChildNodes);
                    }
                }

aspx code: