public int AddCourse(Domain.Course newCourse)
        {
            ICourseDao courseDao = new CourseDao(sessionFactory);
            try
            {
               Course havedCourse=courseDao.GetCourseByTeacherIDAndName(newCourse.courseTeacherID,newCourse.courseName);
               if (havedCourse == null)
               {
                   int courseId = (Int32)courseDao.Save(newCourse);
                   return courseId;
               }
               else {
                   return 0;
               }

            }catch (Exception e) {
                return 0;
            }
        }