how to search by drop down list in ASP.NET MVC : I'm use ASP.NET MVC , I have student table in sql server and I want to do (search by) name and search by grade in student view by using dropdown list the problem is the search not working when i click on search button it's only refresh the page as it with all students.
 This is the student controller code

    public ActionResult Index(string searching,string searchby,int? page)
        {
            var student= db.Supervisors;
            if(searchby=="Name")
            return View(student.Where(x => x.name.Contains(searching)|| searching==null).ToList().ToPagedList(page ?? 1,8));
            else
                return View(student.Where(x => x.grade.Contains(searching) || searching == null).ToList().ToPagedList(page ?? 1, 8));

        }

This is razor code 
 
@using (Html.BeginForm("Index", "student",FormMethod.Get))
    {

        @Html.DropDownList("Searchby", new SelectList(new[] { "Name", "Grade" }))
        @Html.TextBox("search")
        <input type="submit" value="Search" />


    }

