public static Student GetById(int id)
        {
            TrainingManagementDbContext db = new TrainingManagementDbContext();
            var student = db.Students.FirstOrDefault(c => c.Id == id);

            return(student);
        }
        private static bool Update(Student student)
        {
            TrainingManagementDbContext db = new TrainingManagementDbContext();

            db.Students.Attach(student);

            db.Entry(student).State = EntityState.Deleted;

            return(db.SaveChanges() > 0);
        }