public void InitList()
        {
            if (SchoolYearList == null)
            {
                SchoolYearList = new ObservableCollection <string>();
            }
            if (TermList == null)
            {
                TermList = new ObservableCollection <string>();
            }
            foreach (var item in this)
            {
                MainList.Add(item);

                if (!SchoolYearList.Contains(item.SchoolYear))
                {
                    SchoolYearList.Add(item.SchoolYear);
                }
                //过滤出所有的学年和学期
                if (!TermList.Contains(item.Term))
                {
                    TermList.Add(item.Term);
                }
            }
        }
        public void AddRecord(string schoolYear, string term, string subject, string credit, string score, string reScore, string secondFlag, string reLearnScore, string _subjectType)
        {
            var temp = new TRData()
            {
                SchoolYear = schoolYear, Term = term, Subject = subject, Credit = credit, Score = score, SecondFlag = secondFlag, ReScore = reScore, ReLearnScore = reLearnScore, SubjectType = _subjectType
            };

            Add(temp);
            //向主表添加成绩
            MainList.Add(temp);
            if (!SchoolYearList.Contains(schoolYear))
            {
                SchoolYearList.Add(schoolYear);
            }
            //过滤出所有的学年和学期
            if (!TermList.Contains(term))
            {
                TermList.Add(term);
            }
        }