public int RegisterBooking(int ttId, int childId)
        {
            TutoringTime tt = new TutoringTime();
            tt.Id = ttId;
            tt.Child = new Person(childId);

            ttDb = new TutoringTimeDb();

            return ttDb.RegisterBooking(tt);
        }
        public int RegisterBooking(int childId, int tutoringTimeId)
        {
            TutoringTime tt = new TutoringTime();
            tt.Id = tutoringTimeId;
            tt.Child = new Child(childId);

            TutoringTimeDb ttDb = new TutoringTimeDb();

            return ttDb.RegisterBooking(tt);
        }