How to generate Horizontal submenu from database?

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C#

ASP.NET

SQL

i want to generate dynamic menu from database; i can generate one submenu; but i want to generate submenu under submenu like this

Menu>>
SubMenu1>>
SubMenu2>>SubMenu2a
.............SubMenu2b

I have tried this following code..to generate one submenu..

DataSet ds = new DataSet();
        DataTable dt = new DataTable();
        string sql = "Select * from Menu";
        SqlDataAdapter da = new SqlDataAdapter(sql, con);
        da.Fill(ds);
        dt = ds.Tables[0];
        DataRow[] drowpar = dt.Select("ParentID=" + 0);

        foreach (DataRow dr in drowpar)
        {
            menuBar.Items.Add(new MenuItem(dr["MenuName"].ToString(), dr["MenuID"].ToString(), "", dr["MenuLocation"].ToString()));
        }

        foreach (DataRow dr in dt.Select("ParentID >" + 0))
        {
            MenuItem mnu = new MenuItem(dr["MenuName"].ToString(), dr["MenuID"].ToString(), "", dr["MenuLocation"].ToString());
            
                menuBar.FindItem(dr["ParentID"].ToString()).ChildItems.Add(mnu);
            
        }

Database structure is like this:
MenuID MenuName MenuLocation ParentID
1 Menu AA 0
2 SubMenu1 AB 1
3 SubMenu2 AC 1
4 SubMenu2a AD 3
5 SubMenu2b AE 3

Can anyone guide me how to generate submenu under a submenu?