public void AddMark(int Id, float physics, float chemistry, float mathematics, float computing, float english)
        {
            StudentMarks mark = new StudentMarks();

            mark.ID          = Id;
            mark.Physics     = physics;
            mark.Chemistry   = chemistry;
            mark.Mathematics = mathematics;
            mark.Computing   = computing;
            mark.English     = english;
            _Context.StudentMarks.Add(mark);
            _Context.SaveChanges();
        }
        public void DeleteMark(int id)
        {
            StudentMarks mark = _Context.StudentMarks.SingleOrDefault(s => s.ID == id);

            if (mark != null)
            {
                _Context.StudentMarks.Remove(mark);
                _Context.SaveChanges();
            }
            else
            {
                throw new ApplicationException("Cannot find the marks.");
            }
        }
        public void EditMark(float physics, float chemistry, float mathematics, float computing, float english, int ID)
        {
            StudentMarks mark = _Context.StudentMarks.SingleOrDefault(s => s.ID == ID);

            if (mark != null)
            {
                mark.Physics     = physics;
                mark.Chemistry   = chemistry;
                mark.Mathematics = mathematics;
                mark.Computing   = computing;
                mark.English     = english;
                _Context.SaveChanges();
            }
            else
            {
                throw new ApplicationException("Cannot find the marks.");
            }
        }