如同58同城的菜单是怎么做的啊

我写了一下，但是一点小区，小区就没了，保存不了
 protected void Page_Load(object sender, EventArgs e)
        {
           
                InitEnterpriseList();
                   
        }
        protected void InitEnterpriseList()
        {
               #region 添加供热企业              
                SqlConnection cn = new SqlConnection(DataCenter.DataAccess.DbConstants.ConnectionString);
                cn.Open();
                SqlCommand cmd = new SqlCommand("select * from Enterprise", cn);
                SqlDataReader read = null;
                read = cmd.ExecuteReader();
                while (read.Read())
                {
                    LE = new LinkButton();
                    LE.ID = "LE" + read.GetValue(0).ToString();
                    LE.Text = read.GetValue(2).ToString() + "    ";
                    LE.Click += new EventHandler(LinkDistrict_Click);
                    this.td1.Controls.Add(LE);
                }
                cn.Close();  
               #endregion        }     
        private void LinkDistrict_Click(object sender, EventArgs e)
        {
         
            #region 添加小区
            InitEnterpriseList();
            SqlConnection cn = new SqlConnection(DataCenter.DataAccess.DbConstants.ConnectionString);
             cn.Open();
             SqlCommand cmd = new SqlCommand("select * from District where EnterpriseId = " + ((LinkButton)sender).ID.Replace("LE", "") + "", cn);
             SqlDataReader read = null;
             read = cmd.ExecuteReader();
             while (read.Read())
             {
                 LD = new LinkButton();
                 LD.ID = "LD" + read.GetValue(0).ToString();
                 LD.Text = read.GetValue(3).ToString() + "    ";
                 LD.Click += new EventHandler(LinkBuild_Click);
                 this.td2.Controls.Add(LD);
             }
             cn.Close();
           
            #endregion
        }         private void LinkBuild_Click(object sender, EventArgs e)
         {
            
             #region 添加大楼
             SqlConnection cn = new SqlConnection(DataCenter.DataAccess.DbConstants.ConnectionString);
             cn.Open();
             SqlCommand cmd = new SqlCommand("select * from Build where DistrictId = " + ((LinkButton)sender).ID.Replace("LD", "") + "", cn);
             SqlDataReader read = null;
             read = cmd.ExecuteReader();
             while (read.Read())
             {
                 LB = new LinkButton();
                 LB.ID = "LD" + read.GetValue(0).ToString();
                 LB.Text = read.GetValue(3).ToString() + "    ";
                 LB.Click += new EventHandler(LinkUnit_Click);
                 this.td3.Controls.Add(LB);
             }
             cn.Close();
             #endregion
         }