Update data in to database using MVC

This is my insert update code

At the time of inserting insert data successfully but at the time of Update not updateing the data Please See my code below

[HttpPost]

public ActionResult Create(HttpPostedFileBase imageFile, Actor model, string cmd)
{
try
{
if (imageFile != null && imageFile.ContentLength > 0)
{
var fileName = Path.GetFileName(imageFile.FileName);
if (cmd == "Create")
{
model.Image = fileName;
db.Actors.Add(model);
db.SaveChanges();
}
else
{
var actor = db.Actors.Where(m => m.ActorID == model.ActorID).FirstOrDefault();
if (actor != null)
{
actor.Image = fileName;
db.SaveChanges();
}
}

var path = Path.Combine(Server.MapPath("~/Content/Actors/"), model.ActorID.ToString());
if (!Directory.Exists(path))
Directory.CreateDirectory(path);
imageFile.SaveAs(path + "/" + fileName);
}
}
catch { }

return RedirectToAction("Index");
}

UPDATE:


[HttpGet]
public ActionResult Edit(int id)
{
var actor = db.Actors.Where(m => m.ActorID == id).FirstOrDefault();
ViewBag.IsUpdate = true;
return PartialView("_Actor", actor);
}



[HttpPost]
public ActionResult Edit(HttpPostedFileBase imageFile, Actor model, string cmd)
{
if(ModelState.IsValid)
{
try
{
if (imageFile != null && imageFile.ContentLength > 0)
{
var fileName = Path.GetFileName(imageFile.FileName);
if (cmd == "Update")
{
model.Image = fileName;
db.Actors.Add(model);
db.SaveChanges();
}
else
{
var actor = db.Actors.Where(m => m.ActorID == model.ActorID).FirstOrDefault();
if (actor != null)
{
actor.Image = fileName;
db.SaveChanges();
}
}

var path = Path.Combine(Server.MapPath("~/Content/Actors/"), model.ActorID.ToString());
if (!Directory.Exists(path))
Directory.CreateDirectory(path);
imageFile.SaveAs(path + "/" + fileName);
}
}
}
catch { }
return RedirectToAction("Index");
}