How to create multilevel drop down menu in asp.net using c# dynamically.

Database Script :

USE [Menu]
GO
/****** Object:  Table [dbo].[SubMenu]    Script Date: 05/25/2015 17:46:16 ******/
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
CREATE TABLE [dbo].[SubMenu](
	[Id] [int] IDENTITY(1,1) NOT NULL,
	[SubMenuName] [nvarchar](50) NULL,
	[SubMenuUrl] [nvarchar](50) NULL,
	[ParentId] [int] NULL
) ON [PRIMARY]
GO
SET IDENTITY_INSERT [dbo].[SubMenu] ON
INSERT [dbo].[SubMenu] ([Id], [SubMenuName], [SubMenuUrl], [ParentId]) VALUES (1, N'Web Development', N'Web.aspx', 3)
INSERT [dbo].[SubMenu] ([Id], [SubMenuName], [SubMenuUrl], [ParentId]) VALUES (2, N'SEO Services', N'Seo.aspx', 3)
INSERT [dbo].[SubMenu] ([Id], [SubMenuName], [SubMenuUrl], [ParentId]) VALUES (3, N'Mobile Apps', N'Mob.aspx', 3)
SET IDENTITY_INSERT [dbo].[SubMenu] OFF
/****** Object:  Table [dbo].[Menu]    Script Date: 05/25/2015 17:46:16 ******/
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
CREATE TABLE [dbo].[Menu](
	[Id] [int] IDENTITY(1,1) NOT NULL,
	[MenuName] [nvarchar](50) NULL,
	[MenuUrl] [nvarchar](50) NULL
) ON [PRIMARY]
GO
SET IDENTITY_INSERT [dbo].[Menu] ON
INSERT [dbo].[Menu] ([Id], [MenuName], [MenuUrl]) VALUES (1, N'Home', N'Home.aspx')
INSERT [dbo].[Menu] ([Id], [MenuName], [MenuUrl]) VALUES (2, N'About Us', N'About.aspx')
INSERT [dbo].[Menu] ([Id], [MenuName], [MenuUrl]) VALUES (3, N'Services', N'Services.aspx')
INSERT [dbo].[Menu] ([Id], [MenuName], [MenuUrl]) VALUES (4, N'Testimonial', N'Testimonial.aspx')
INSERT [dbo].[Menu] ([Id], [MenuName], [MenuUrl]) VALUES (5, N'Contact Us', N'Contact.aspx')
SET IDENTITY_INSERT [dbo].[Menu] OFF
/****** Object:  Table [dbo].[ChildSubMenu]    Script Date: 05/25/2015 17:46:16 ******/
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
CREATE TABLE [dbo].[ChildSubMenu](
	[Id] [int] IDENTITY(1,1) NOT NULL,
	[ChildSubMenuName] [nvarchar](50) NULL,
	[ChildSubMenuUrl] [nvarchar](50) NULL,
	[SubParentId] [int] NULL
) ON [PRIMARY]
GO
SET IDENTITY_INSERT [dbo].[ChildSubMenu] ON
INSERT [dbo].[ChildSubMenu] ([Id], [ChildSubMenuName], [ChildSubMenuUrl], [SubParentId]) VALUES (1, N'Web Designing', N'Web.aspx', 3)
INSERT [dbo].[ChildSubMenu] ([Id], [ChildSubMenuName], [ChildSubMenuUrl], [SubParentId]) VALUES (2, N'Web Redisigning', N'Des.aspx', 3)
INSERT [dbo].[ChildSubMenu] ([Id], [ChildSubMenuName], [ChildSubMenuUrl], [SubParentId]) VALUES (3, N'Ecomments', N'Ecom.aspx', 3)
SET IDENTITY_INSERT [dbo].[ChildSubMenu] OFF

CSS :

<style>
        /* Base Styles */#cssmenu > ul, #cssmenu > ul li, #cssmenu > ul ul
        {
            list-style: none;
            margin: 0;
            padding: 0;
        }
        #cssmenu > ul
        {
            position: relative;
            z-index: 597;
        }
        #cssmenu > ul li
        {
            float: left;
            min-height: 1px;
            line-height: 1.3em;
            vertical-align: middle;
        }
        #cssmenu > ul li.hover, #cssmenu > ul li:hover
        {
            position: relative;
            z-index: 599;
            cursor: default;
        }
        #cssmenu > ul ul
        {
            visibility: hidden;
            position: absolute;
            top: 100%;
            left: 0;
            z-index: 598;
            width: 100%;
        }
        #cssmenu > ul ul li
        {
            float: none;
        }
        #cssmenu > ul ul ul
        {
            top: 1px;
            left: 99%;
        }
        #cssmenu > ul li:hover > ul
        {
            visibility: visible;
        }
        /* Align last drop down RTL */#cssmenu > ul > li.last ul ul
        {
            left: auto !important;
            right: 99%;
        }
        #cssmenu > ul > li.last ul
        {
            left: auto;
            right: 0;
        }
        #cssmenu > ul > li.last
        {
            text-align: right;
        }
        /* Theme Styles */#cssmenu > ul
        {
            border-top: 4px solid #3fa338;
            font-family: Calibri, Tahoma, Arial, sans-serif;
            font-size: 14px;
            background: #1e1e1e;
            background: -moz-linear-gradient(top, #1e1e1e 0%, #040404 100%);
            background: -webkit-gradient(linear, left top, left bottom, color-stop(0%, #1e1e1e), color-stop(100%, #040404));
            background: -webkit-linear-gradient(top, #1e1e1e 0%, #040404 100%);
            background: linear-gradient(top, #1e1e1e 0%, #040404 100%);
            width: auto;
            zoom: 1;
        }
        #cssmenu > ul:before
        {
            content: '';
            display: block;
        }
        #cssmenu > ul:after
        {
            content: '';
            display: table;
            clear: both;
        }
        #cssmenu > ul li a
        {
            display: inline-block;
            padding: 10px 22px;
        }
        #cssmenu > ul > li.active, #cssmenu > ul > li.active:hover
        {
            background-color: #3fa338;
        }
        #cssmenu > ul > li > a:link, #cssmenu > ul > li > a:active, #cssmenu > ul > li > a:visited
        {
            color: #ffffff;
        }
        #cssmenu > ul > li > a:hover
        {
            color: #ffffff;
        }
        #cssmenu > ul ul ul
        {
            top: 0;
        }
        #cssmenu > ul li li
        {
            background-color: #ffffff;
            border-bottom: 1px solid #ebebeb;
            font-size: 12px;
        }
        #cssmenu > ul li.hover, #cssmenu > ul li:hover
        {
            background-color: #F5F5F5;
        }
        #cssmenu > ul > li.hover, #cssmenu > ul > li:hover
        {
            background-color: #3fa338;
            -webkit-box-shadow: inset 0 -3px 0 rgba(0, 0, 0, 0.15);
            -moz-box-shadow: inset 0 -3px 0 rgba(0, 0, 0, 0.15);
            box-shadow: inset 0 -3px 0 rgba(0, 0, 0, 0.15);
        }
        #cssmenu > ul a:link, #cssmenu > ul a:visited
        {
            color: #9a9a9a;
            text-decoration: none;
        }
        #cssmenu > ul a:hover
        {
            color: #9a9a9a;
        }
        #cssmenu > ul a:active
        {
            color: #9a9a9a;
        }
        #cssmenu > ul ul
        {
            border: 1px solid #CCC \9;
            -webkit-box-shadow: 0 0px 2px 1px rgba(0, 0, 0, 0.15);
            -moz-box-shadow: 0 0px 2px 1px rgba(0, 0, 0, 0.15);
            box-shadow: 0 0px 2px 1px rgba(0, 0, 0, 0.15);
            width: 150px;
        }
    </style>

Javascript :

 <script src="http://code.jquery.com/jquery-latest.min.js" type="text/javascript"></script>

Aspx Page :

<body>
    <form id="form1" runat="server">
        <div id='cssmenu' runat="server">
        </div>
    </form>
</body>

C# Page :

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Data;
using System.Data.SqlClient;
using System.Text;
using System.Configuration;

public partial class menu : System.Web.UI.Page
{
    public string connectionstring = ConfigurationManager.AppSettings["tute"].ToString();
    protected void Page_Load(object sender, EventArgs e)
    {
        if (!IsPostBack)
        {
            GetMenuData();
        }
    }
    /// 
    /// This method will return data for menu creation
    /// 
    /// 
    public void GetMenuData()
    {
        StringBuilder objstr = new StringBuilder();
        List<Menu> objpmenu = new List<Menu>();
        List<SubMenu> objsmenu = new List<SubMenu>();
        List<ChildSubMenu> objcmenu = new List<ChildSubMenu>();
        objpmenu = GetMenu();
        objsmenu = GetSubMenu();
        objcmenu = GetChildSubMenu();

        objstr.Append("<ul>");

        foreach (Menu _pitem in objpmenu)
        {
            objstr.Append("<li><a href='" + _pitem.MenuUrl + "'><span>" + _pitem.MenuName + "</span></a>");           
            
            var subitem = objsmenu.Where(m => m.ParentId == _pitem.Id).ToList();
            if (subitem.Count > 0)
            {
                objstr.Append("<ul>");
                foreach (var _sitem in subitem)
                {
                    objstr.Append("<li class='has-sub'><a href='" + _sitem.SubMenuUrl + "'><span>" + _sitem.SubMenuName + "</span></a>");

                    var childsubitem = objcmenu.Where(s => s.SubParentId == _sitem.Id).ToList();
                    if (childsubitem.Count > 0)
                    {
                        objstr.Append("<ul>");
                        foreach (var _citem in childsubitem)
                        {
                            objstr.Append("<li class='has-sub'><a href='" + _citem.ChildSubMenuUrl + "'><span>" + _citem.ChildSubMenuName + "</span></a></li>");
                        }
                        objstr.Append("</ul>");
                    } 

                    objstr.Append("</li>");
                }
                objstr.Append("</ul>");
            }        
            
            objstr.Append("</li>");
        }

        objstr.Append("</ul>");

        cssmenu.InnerHtml = objstr.ToString();
    }
    /// 
    /// Get Data from Menu table
    /// 

    /// 
    public List<Menu> GetMenu()
    {
        List<Menu> objmenu = new List<Menu>();
        DataTable _objdt = new DataTable();
        string querystring = "select * from Menu;";
        SqlConnection _objcon = new SqlConnection(connectionstring);
        SqlDataAdapter _objda = new SqlDataAdapter(querystring, _objcon);
        _objcon.Open();
        _objda.Fill(_objdt);
        if (_objdt.Rows.Count > 0)
        {
            for (int i = 0; i < _objdt.Rows.Count; i++)
            {
                objmenu.Add(new Menu { Id = (int)_objdt.Rows[i]["Id"], MenuName = _objdt.Rows[i]["MenuName"].ToString(), MenuUrl = _objdt.Rows[i]["MenuUrl"].ToString() });
            }
        }
        return objmenu;
    }
    /// 
    /// Get data from SubMenu table
    /// 

    /// 
    public List<SubMenu> GetSubMenu()
    {
        List<SubMenu> objmenu = new List<SubMenu>();
        DataTable _objdt = new DataTable();
        string querystring = "select * from SubMenu;";
        SqlConnection _objcon = new SqlConnection(connectionstring);
        SqlDataAdapter _objda = new SqlDataAdapter(querystring, _objcon);
        _objcon.Open();
        _objda.Fill(_objdt);
        if (_objdt.Rows.Count > 0)
        {
            for (int i = 0; i < _objdt.Rows.Count; i++)
            {
                objmenu.Add(new SubMenu { Id = (int)_objdt.Rows[i]["Id"], ParentId = (int)_objdt.Rows[i]["ParentId"], SubMenuName = _objdt.Rows[i]["SubMenuName"].ToString(), SubMenuUrl = _objdt.Rows[i]["SubMenuUrl"].ToString() });
            }
        }
        return objmenu;
    }
    /// 
    /// Get data from childSubmenu table
    /// 

    /// 
    public List<ChildSubMenu> GetChildSubMenu()
    {
        List<ChildSubMenu> objmenu = new List<ChildSubMenu>();
        DataTable _objdt = new DataTable();
        string querystring = "select * from ChildSubMenu;";
        SqlConnection _objcon = new SqlConnection(connectionstring);
        SqlDataAdapter _objda = new SqlDataAdapter(querystring, _objcon);
        _objcon.Open();
        _objda.Fill(_objdt);
        if (_objdt.Rows.Count > 0)
        {
            for (int i = 0; i < _objdt.Rows.Count; i++)
            {
                objmenu.Add(new ChildSubMenu { SubParentId = (int)_objdt.Rows[i]["SubParentId"], ChildSubMenuName = _objdt.Rows[i]["ChildSubMenuName"].ToString(), ChildSubMenuUrl = _objdt.Rows[i]["ChildSubMenuUrl"].ToString() });
            }
        }
        return objmenu;
    }


    /*Menu Class*/
    public class Menu
    {
        public int Id { get; set; }
        public string MenuName { get; set; }
        public string MenuUrl { get; set; }
    }
    public class SubMenu
    {
        public int Id { get; set; }
        public int ParentId { get; set; }
        public string SubMenuName { get; set; }
        public string SubMenuUrl { get; set; }
    }
    public class ChildSubMenu
    {
        public int SubParentId { get; set; }
        public string ChildSubMenuName { get; set; }
        public string ChildSubMenuUrl { get; set; }
    }


}