public function up()
 {
     $this->load->helper('url');
     $is_currently_running = $this->db->where('key', 'current_migration')->where('description', (string) $this->migration_num)->get('settings')->num_rows();
     if (array_diff(array_keys($fields), $this->db->list_fields('assess_results')) && !$is_currently_running) {
         $this->db->update('settings', array('description' => (string) $this->migration_num), array('key' => 'current_migration'));
         $this->dbforge->add_column('assess_results', $this->fields);
         AssessHelper::runBackground(site_url('/crons/Fill_assess_results_new_fields/'));
     }
 }
 public function up()
 {
     $this->load->helper('url');
     AssessHelper::runBackground(site_url('/crons/Fill_assess_results_new_fields/'));
 }