public ExamList AddExamlist(ExamList examlist)
 {
     OTSDBDAL otsdbDAL = new OTSDBDAL();
     otsdbDAL.ExamList.Add(examlist);
     otsdbDAL.SaveChanges();
     return examlist;
 }
 public Article UploadArticle(Article article)
 {
     OTSDBDAL otsdbDAL = new OTSDBDAL();
     otsdbDAL.ArticleList.Add(article);
     otsdbDAL.SaveChanges();
     return article;
 }
 /* Create by Zhang Cong */
 public UserInfo SignUp(UserInfo userInfo)
 {
     OTSDBDAL otsdbDAL = new OTSDBDAL();
     otsdbDAL.UserInfoList.Add(userInfo);
     otsdbDAL.SaveChanges();
     return userInfo;
 }
 public UserInfo Remove(UserInfo userInfo)
 {
     OTSDBDAL otsdbDAL = new OTSDBDAL();
     otsdbDAL.UserInfoList.Remove(userInfo);
     otsdbDAL.SaveChanges();
     return userInfo;
 }
 public void Del(UserInfo userInfo)
 {
     OTSDBDAL otsdbDAL = new OTSDBDAL();
     otsdbDAL.UserInfoList.Attach(userInfo);
     otsdbDAL.UserInfoList.Remove(userInfo);
     otsdbDAL.SaveChanges();
 }
 public Comment UploadComment(Comment comment)
 {
     OTSDBDAL otsdbDAL = new OTSDBDAL();
     otsdbDAL.CommentList.Add(comment);
     otsdbDAL.SaveChanges();
     return comment;
 }
 public List<Exam> AddExam(List<Exam> examList)
 {
     OTSDBDAL otsdbDAL = new OTSDBDAL();
     foreach(Exam exam in examList)
     {
         otsdbDAL.Exam.Add(exam);
         otsdbDAL.SaveChanges();
     }
     return examList;
 }
 public List<ExamList> GetExamList()
 {
     OTSDBDAL otsdbDAL = new OTSDBDAL();
     return otsdbDAL.ExamList.ToList();
 }
 public List<Article> GetArticleList()
 {
     OTSDBDAL otsdbDAL = new OTSDBDAL();
     return otsdbDAL.ArticleList.ToList();
 }
 public List<UserInfo> GetUserInfoList()
 {
     OTSDBDAL otsdbDAL = new OTSDBDAL();
     return otsdbDAL.UserInfoList.ToList();
 }
 public List<Comment> GetCommentList()
 {
     OTSDBDAL otsdbDAL = new OTSDBDAL();
     return otsdbDAL.CommentList.ToList();
 }