C#

foreach(DataRow row in DataTable)
{
  string[] parts = row["ColumnName"].ToString().Split('.');

  TreeNode baseNode = RootNode;//root of tree view
  foreach(string s in parts)
  {

     TreeNode temp = CheckNodeExists(s, baseNode);
     if(temp == null)
        temp = baseNode.AddNode("ID", "Name", "Image")//what ever params you need to use
     baseNode = temp;
  }
}


public TreeNode CheckNodeExists(string nodeText, TreeNodeCollection nodes)
{
    if(nodes == null || nodes.Count == 0)
       return null;

     foreach(TreeNode node in nodes)
        if(node.Text == nodeText)
               return node;

      return null;
}