SaveChanges is not working on modify the data - asp.net-mvc

Question

when i try to save the the new Student object. it works fine but when i am trying to modify the data, it doesn't update the data. Instead none error is thrown on SaveChanges.
i am using code first approach (using mysql provider) and here it is the complete source.
https://www.dropbox.com/s/e34frntq8u5gsmh/SchoolManagementSystem.rar?dl=0
my tired code is this :
public ActionResult Create(Student student, HttpPostedFileBase Image)
{
try
{
if (ModelState.IsValid)
{
student = db.Students.Find(student.ID);
if (student.ID > 0)
{
db.Entry(student).State = EntityState.Modified;
db.SaveChanges();
}
else
{
if (student.Basic == null) student.Basic = new BasicInformation();
if (Image != null && Image.ContentLength > 0)
{
student.Basic.PictureUrl = Image.FileName;
string path = Server.MapPath(("~/Images/"));
Image.SaveAs(path + Image.FileName);
}
db.Students.Add(student);
db.SaveChanges();
}
return RedirectToAction("StudentList");
}
}
catch (RetryLimitExceededException /* dex */)
{
//Log the error (uncomment dex variable name and add a line here to write a log.
ModelState.AddModelError("", "Unable to save changes. Try again, and if the problem persists see your system administrator.");
}
return View(student);
}

Answer 1

This seems to be the modify scenario :
if (student.ID > 0)
{
db.Entry(student).State = EntityState.Modified;
db.SaveChanges();
}
Eliminate this line of code :
db.Entry(student).State = EntityState.Modified;
and instead add code that updates the object with the new modified values.
Hope this helps.

Answer 2

By this line
student = db.Students.Find(student.ID);
you overwrite the student that enters the method and you lose all changes. You can do two things in stead:
Only remove the line. Your code will now attach the modified student as EntityState.Modified.
Fetch the original student from the database and copy the modified values to it:
var studentOrg = db.Students.Find(student.ID);
db.Entry(studentOrg).CurrentValues.SetValues(student);
(both SaveChanges calls can be moved to one just before return RedirectToAction...)
Option 1 will generate an update statement containing all Student's fields, but not have a roundtrip to get the original record.
Option 2 has this roundtrip, but only updates modified fields. This (option 2) can be beneficial when changes are audited or when concurrency should be minimized.