TreeView在绑定数据时如何限制子节点下的子节点最多绑定的层数

public void LoadFileType()
{
DataSet ds = new b2ccms_BLL.b2ccms_userMemberBLL().GetListZ("*", "u_id='" + M_Id + "'");
TreeNode tn = new TreeNode();
DataTable table = ds.Tables[0]; //查询第一节点数据
foreach (DataRow dr in table.Rows) //循环绑定节点并查询子节点
{
TreeNode tr = new TreeNode();
tn.Text = dr["u_name"].ToString();
tn.Value = dr["u_name"].ToString();
LoadChildNoed(dr["u_name"].ToString(), tn); //加载子节点
tn.ChildNodes.Add(tn);
}
tn.Expanded = true;
TreeView1.Nodes.Add(tn);
}

    //加载子节点
    public void LoadChildNoed(string Pid, TreeNode tr)
    {
        DataSet ds = new b2ccms_BLL.b2ccms_userMemberBLL().GetListZ("*", "u_referess='" + Pid + "'");
        DataTable table = ds.Tables[0];     //查询子节点数据
        foreach (DataRow dr in table.Rows)   //循环绑定节点并查询子节点
        {
            TreeNode td = new TreeNode();
            td.Value = dr["u_name"].ToString();
            td.Text = dr["u_name"].ToString();
            td.Expanded=false;
            LoadChildNoed(dr["u_name"].ToString(), td);   //递归绑定子节点
            tr.ChildNodes.Add(td);
        }
    }
            如何让子节点最多绑定到9层，9层之后的就不在显示了

https://ask.csdn.net/questions/714834