Repeater+SQL查询3层嵌套

ASPX
        <ul>
        <asp:Repeater ID="TemRepeater1" runat="server" OnItemDataBound="TemRepeater1_ItemDataBound">
        <ItemTemplate>
        <li>
            <div><%#Eval("LibraryName")%></div>
            
            <asp:Repeater ID="TemRepeater2" runat="server" OnItemDataBound="TemRepeater2_ItemDataBound">
            <HeaderTemplate><ul></HeaderTemplate>
            <FooterTemplate></ul></FooterTemplate>
            <ItemTemplate>
            <li>
                <div><%#Eval("SubjectName")%></div>
                    
                <asp:Repeater ID="TemRepeater3" runat="server">
                <HeaderTemplate><ul></HeaderTemplate>
                <FooterTemplate></ul></FooterTemplate>
                    <ItemTemplate>
                    <li>
                    <div><%#Eval("Title") %></div>
                    </li>
                    </ItemTemplate>
                </asp:Repeater>
                
                </li>
                </ItemTemplate>
            </asp:Repeater>
            
            </li>
            </ItemTemplate>
        </asp:Repeater>
        </ul>

CS

        protected void Page_Load(object sender, EventArgs e)
        {
            string ConnectionString = ConfigurationManager.AppSettings["ConnectionString"].ToString();
            SqlConnection conn = new SqlConnection(ConnectionString);

            string bStr = "select * from Library";
            SqlDataAdapter rs = new SqlDataAdapter(bStr, conn);
            conn.Open();
            DataSet rd = new DataSet();
            rs.Fill(rd);
            TemRepeater1.DataSource = rd;
            TemRepeater1.DataBind();
            conn.Close();
            Listbind();
        }
        protected void TemRepeater1_ItemDataBound(object sender, RepeaterItemEventArgs e)
        {
            if (e.Item.ItemType == ListItemType.Item || e.Item.ItemType == ListItemType.AlternatingItem)
            {
                string preid = ((DataRowView)e.Item.DataItem).Row["ID"].ToString();//获得对应ID
                Repeater r2 = (Repeater)e.Item.FindControl("TemRepeater2");//找到要绑定数据的Repeater
                if (r2 != null)
                {
                    string ConnectionString = ConfigurationManager.AppSettings["ConnectionString"].ToString();
                    SqlConnection sc = new SqlConnection(ConnectionString);
                    string scmd = "select * from Subject where ParentID=" + preid + " order by ID asc";

                    SqlDataAdapter srs = new SqlDataAdapter(scmd, sc);
                    sc.Open();
                    DataSet srd = new DataSet();
                    srs.Fill(srd);

                    r2.DataSource = srd;
                    r2.DataBind();
                    sc.Close();
                }
            }
        }
        protected void TemRepeater2_ItemDataBound(object sender, RepeaterItemEventArgs e)
        {
            if (e.Item.ItemType == ListItemType.Item || e.Item.ItemType == ListItemType.AlternatingItem)
            {

                string preid = ((DataRowView)e.Item.DataItem).Row["id"].ToString();//获得对应ID

                Repeater r3 = (Repeater)e.Item.FindControl("TemRepeater3");//找到要绑定数据的Repeater
                if (r3 != null)
                {
                    string ConnectionString = ConfigurationManager.AppSettings["ConnectionString"].ToString();
                    SqlConnection sc = new SqlConnection(ConnectionString);
                    string scmd = "select * from Title where SubjectID=" + preid + " order by ID asc";

                    SqlDataAdapter srs = new SqlDataAdapter(scmd, sc);
                    sc.Open();
                    DataSet srd = new DataSet();
                    srs.Fill(srd);

                    r3.DataSource = srd;
                    r3.DataBind();
                    sc.Close();
                }

            }
        }