从三张表中联合生成动态树(三级)

    private void BindTree()
    {
        DataSet ds = GetTreeViewData();
        TreeView1.ShowCheckBoxes = TreeNodeTypes.All;
        foreach (DataRow masterRow in ds.Tables["province"].Rows)
        {
            TreeNode masterNode = new TreeNode((string)masterRow["province"]);
            TreeView1.Nodes.Add(masterNode);
            foreach (DataRow childRow in masterRow.GetChildRows("Children"))
            {
                TreeNode childNode = new TreeNode((string)childRow["city"]);
                masterNode.Expanded = false;
                masterNode.ChildNodes.Add(childNode);
                foreach (DataRow childReow1 in childRow.GetChildRows("Children1"))
                {
                    TreeNode childNode1 = new TreeNode((string)childReow1["area"]);
                    childNode.Expanded = false;
                    childNode.ChildNodes.Add(childNode1);
                }
            }
        }
    }
   private DataSet GetTreeViewData()
    {
  
       string constring = ConfigurationManager.ConnectionStrings["ConnectionString"].ConnectionString;
       SqlConnection conn = new SqlConnection(constring);
       conn.Open();       SqlDataAdapter cn1 = new SqlDataAdapter("select * from province",conn);
       SqlDataAdapter cn2 = new SqlDataAdapter("SELECT * FROM city",conn);
       SqlDataAdapter cn3 = new SqlDataAdapter("SELECT * FROM area", conn);
       DataSet ds = new DataSet();
       cn1.Fill(ds, "province");
       cn2.Fill(ds, "city");
       cn3.Fill(ds, "area");
       ds.Relations.Add("Children", ds.Tables["province"].Columns["provinceid"], ds.Tables["city"].Columns["father"]);
       ds.Relations.Add("Children1", ds.Tables["city"].Columns["cityID"], ds.Tables["area"].Columns["father"]);
       return ds;
          }