//退课
 public bool DropCourse(int studentId, int courseId)
 {
     ICourseDao courseDao = new CourseDao(sessionFactory);
     Course selectedCourse = courseDao.Get(courseId);
     ISelectionDao selectionDao = new SelectionDao(sessionFactory);
     SelectionID selectionID = new SelectionID {
         selectionStudentID=studentId,
         selectionCourseID=courseId,
         selectionStudyYear=selectedCourse.courseStudyYear,
          selectionTerm=selectedCourse.courseTerm
     };
     Selection selection=selectionDao.Get(selectionID);
     if (null != selection)
     {
         try
         {
             selectionDao.Delete(selection);
             return true;
         }
         catch (Exception e) {
             return false;
         }
     }
     else {
         return false;
     }
 }
        public Selection GetSelectionByID(SelectionID selectionId)
        {
            ISelectionDao selectionDao = new SelectionDao(sessionFactory);
            try
            {
                return selectionDao.Get(selectionId);

            }
            catch (Exception e)
            {
                return null;
            }
        }
 public int GetStudentScore(object selectionID)
 {
     ISelectionDao selectionDao= new SelectionDao(sessionFactory);
     try
     {
         Selection selection= selectionDao.Get(selectionID);
         return selection.selectionScore;
     }
     catch (Exception e)
     {
         return -1;
     }
 }
 public void ScoreAStudent()
 {
     int score = 60;
     string studyYear = "2012~2013";
     string term = "上";
     int courseId =1000;
     int studentId = 10000002;
     ISelectionDao selectionDao = new SelectionDao(sessionFactory);
     SelectionID seletionID = new SelectionID {
          selectionStudentID=studentId,
          selectionCourseID= courseId,
          selectionStudyYear=studyYear,
          selectionTerm=term
     };
     Selection selectedSelection = selectionDao.Get(seletionID);
     bool success;
     if (true == selectedSelection.selectionScorePermit)
     {
         selectedSelection.selectionScore = score;
         success = teacherController.ScoreStudentCourse(selectedSelection);
     }
     else {
         success=false;
     }
     Assert.AreEqual(true, success);
 }