public List<Semester> GetAllSemesters()
        {
            try
            {
                List<Semester> semester = new List<Semester>();
                connection.Open();
                string semesterQuery = "select * from t_Semester";
                command.CommandText = semesterQuery;
                SqlDataReader semesterReader = command.ExecuteReader();
                while (semesterReader.Read())
                {
                    Semester aSemester = new Semester();
                    aSemester.SemesterId = Convert.ToInt16(semesterReader[0].ToString());
                    aSemester.SemesterName = semesterReader[1].ToString();
                    semester.Add(aSemester);
                }

                return semester;

            }
            finally
            {
                connection.Close();
            }
        }
        public Semester GetSemester(int id)
        {
            List<Semester>semesters=new List<Semester>();
            semesters = GetAllSemesters();
            Semester aSemester = new Semester();
            foreach (Semester semester in semesters)
            {
                if(semester.SemesterId==id)
                {
                    aSemester.SemesterId = semester.SemesterId;
                    aSemester.SemesterName = semester.SemesterName;
                    return aSemester;
                }

            }
            return aSemester;
        }