public function __construct()
 {
     parent::__construct('topic', 'topic_id');
 }
 public function __construct()
 {
     parent::__construct('student_mark', 'id');
 }
 public function __construct()
 {
     parent::__construct('storage_answer', 'storage_answer_id');
 }
 public function __construct()
 {
     parent::__construct('student_info', 'student_id');
 }
 public function __construct()
 {
     parent::__construct('academic_year', 'academic_id');
 }
 public function __construct()
 {
     parent::__construct('block', 'block_id');
 }
 public function __construct()
 {
     parent::__construct('exam', 'exam_id');
 }
 public function __construct()
 {
     parent::__construct('answer', 'answer_id');
 }
 public function __construct()
 {
     parent::__construct('student_answer', 'answer_student_id');
 }
 public function __construct()
 {
     parent::__construct('users', 'username');
 }
 public function __construct()
 {
     parent::__construct('storage_question', 'storage_question_id');
 }
 public function __construct()
 {
     parent::__construct('subjects', 'subjects_id');
 }
 public function __construct()
 {
     parent::__construct('question', 'question_id');
 }
 public function __construct()
 {
     parent::__construct('topic_files', 'id');
 }
 public function __construct()
 {
     parent::__construct('topic_manage', 'topic_manage_id');
 }
 public function getAll($start = null, $count = null, $cached = true)
 {
     $this->db->join('block', 'block.block_id = class.block_id');
     $this->db->select('block.title');
     return parent::getAll($start, $count, $cached);
 }
 public function __construct()
 {
     parent::__construct('student_topic', 'id');
 }