//Adding new entry between Teacher-And-SchoolClassSubject in table TeacherSchoolClassSubject
        public void AddNewEntry(int teacherId, int schoolClassId, int subjectId)
        {
            int entryId = _schoolClassSubjectRepository.CheckEntryBetweenSchoolClassAndSubjectInDataBase(schoolClassId, subjectId);

            if (entryId != 0) //Creating entry in table TeacherSchoolClassSubjects
            {
                _context.TeacherSchoolClassSubjects.Add(new TeacherSchoolClassSubject {
                    SchoolClassSubjectId = entryId, TeacherId = teacherId
                });
                _context.SaveChangesAsync();
            }
            else if (entryId == 0) // If entry between SchoolClass-And-Subject doesnt exists, create it and add entry to table TeacherSchoolClassSubjects
            {
                _schoolClassSubjectRepository.AddNewEntry(schoolClassId, subjectId);
                _context.TeacherSchoolClassSubjects.Add(new TeacherSchoolClassSubject {
                    SchoolClassSubjectId = entryId, TeacherId = teacherId
                });
                _context.SaveChangesAsync();
            }
        }
        //Checking entry between SchoolClass and Subject in SchoolClassSubject table
        //Проверка есть ли запись в таблице SchoolClass-И-Subject
        public int CheckEntryBetweenSchoolClassAndSubjectInDataBase(string schoolClassNumber, string SubjectNumber)
        {
            int entryId = _schoolClassSubjectRepository.CheckEntryBetweenSchoolClassAndSubjectInDataBase(_hashidService.Decode(schoolClassNumber), _hashidService.Decode(SubjectNumber));

            if (entryId != 0)
            {
                return(entryId);
            }
            else
            {
                return(0);
            }
        }