public IHttpActionResult AddStudent(int id,AddStudentViewModel student)
        {
            AddStudentDTO newStudent = new AddStudentDTO();
            newStudent.TemplateID = student.TemplateID;
            newStudent.Semester = student.Semester;
            newStudent.SSN = student.SSN;

            try
            {
                _context.AddStudentToCourse(newStudent);
                var location = Url.Link("StudentInCourse", new { id = id });
                return Created(location, student.SSN);
            }
            catch(Exception ex)
            {
                if (ex is KeyNotFoundException)
                    return NotFound();
                else
                    return InternalServerError();
            }
        }
        public void AddStudentToCourse(AddStudentDTO dto)
        {
            var course = (from c in _db.Courses
                          join t in _db.CourseTemplate on c.TemplateID equals t.TemplateID
                          where c.Semester == dto.Semester
                          select c).SingleOrDefault();

            if (course == null)
                throw new KeyNotFoundException();

            var student = _db.Student.SingleOrDefault(x => x.SSN == dto.SSN);

            if (student == null)
            {
                throw new KeyNotFoundException();
            }

            Entities.StudentInCourse toInsert = new Entities.StudentInCourse();
            toInsert.CourseID = course.ID;
            toInsert.StudentID = student.SSN;

            _db.StudentInCourse.Add(toInsert);
            _db.SaveChanges();
        }