public void UpdateStudent(StudentDTO student, int studentGroupId)
 {
     using (var uow = UnitOfWorkProvider.Create()) {
         var appStudent = Mapper.Map <Student>(student);
         if (studentGroupId > 0)
         {
             appStudent.StudentGroup = StudentGroupRepository.GetById(studentGroupId);
         }
         Repository.Update(appStudent);
         uow.Commit();
     }
 }