fill #html.dropdownlist from other #html.dropdownlist by same table using ajax - asp.net-mvc-4

Question

I'm working on some search/filter functionality by using dropdownlists
the question is how can i populate the second dropdownlist by choosing item in first ddl
if all data saved in ont table.
i have table of CarType that has manufacturer, model and year.
when i choose a manufacturer in first ddl the second will filled by models of this manufacturer.
Code i have in Controller:
public ActionResult Search(string manufacturer, string carModel, string searchString, string gear)
{
using (CarTypesLogic logic = new CarTypesLogic())
{
IEnumerable<CarType> allCarTypes = logic.GetAllCarTypes();
var manufacturerList = new List<string>();
var modelList = new List<string>();
var gearList = new List<string>();
var foundManufacturer = from maker in allCarTypes
orderby maker.Manufacturer
select maker.Manufacturer;
var foundModels = from model in allCarTypes
orderby model.Model
select model.Model;
var foundGears = from transmission in allCarTypes
select transmission.Gear;
manufacturerList.AddRange(foundManufacturer.Distinct());
modelList.AddRange(foundModels.Distinct());
gearList.AddRange(foundGears.Distinct());
ViewBag.Manufacturer = new SelectList(manufacturerList);
ViewBag.Gear = new SelectList(gearList);
ViewBag.carModel = new SelectList(modelList);
var foundCars = from car in allCarTypes select car;
if (!String.IsNullOrEmpty(manufacturer))
{
foundCars = foundCars.Where(car => car.Manufacturer == manufacturer);
}
if (!String.IsNullOrEmpty(gear))
{
foundCars = foundCars.Where(car => car.Gear == gear);
}
if (!String.IsNullOrEmpty(searchString))
{
foundCars = foundCars.Where(car => car.Manufacturer.ToLower().Contains(searchString.ToLower()));
}
if (!String.IsNullOrEmpty(carModel))
{
foundCars = foundCars.Where(car => car.Model == carModel);
}
return View(foundCars);
}
}
My cshtml code:
#using (Html.BeginForm())
{
<p>
Manufacturer: #Html.DropDownList("manufacturer", String.Empty)
Model: #Html.DropDownList("carModel",String.Empty)
Gear: #Html.DropDownList("gear", String.Empty)
Free Type: #Html.TextBox("SearchString")
<br />
<input type="submit" value="Search"/>
</p>
}

Answer 1

you need to use Cascaded DropDownList.
here are few examples:
http://mvc4beginner.com/Sample-Code/Cascading-DropDownList/APS-.NET-MVC-Cascading-DropdownLists-Using-LINQ.html
http://code.msdn.microsoft.com/Cascading-DropDownList-in-833683f9/sourcecode?fileId=48387&pathId=451527572
http://www.itorian.com/2013/02/cascading-dropdownlist-in-aspnet-mvc.html