Populate TreeView from DataBase

It will probably be something like this. Give some more detail as to what exactly you want to do if you need more.

//In Page load
foreach (DataRow row in topics.Rows)
{
    TreeNode node = new TreeNode(dr["name"], dr["topicId"])
    node.PopulateOnDemand = true;

     TreeView1.Nodes.Add(node);
 }
 ///
 protected void PopulateNode(Object sender, TreeNodeEventArgs e)
 {
     string topicId = e.Node.Value;
     //select from topic where parentId = topicId.
     foreach (DataRow row in topics.Rows)
     {
         TreeNode node = new TreeNode(dr["name"], dr["topicId"])
         node.PopulateOnDemand = true;

         e.Node.ChildNodes.Add(node);
     }

 }