How to access database in custom library codeigniter

1. Create your library, example “sample.php”

defined('BASEPATH') OR exit('No direct script access allowed');

class Sample
{
 protected $ci;

 public function __construct()
 {
        $this->ci =& get_instance();
 }

 public function debug($id)
 {
  $table = $this->ci->db->get_where('table', array('id' => $id))->num_rows();

  if (empty($table)) {
   $result = 'table is empty';
  } else {
   $result = $table;
  }

  return $result;
 }

}

2. Load your library in controller

defined('BASEPATH') OR exit('No direct script access allowed');

class Testing extends READY_Controller {

 public $page = 'Training';

 public function __construct()
 {
  parent::__construct();

  //Load Dependencies
  $this->load->library('sample');
 }

 public function index()
 {
  $data['result'] = $this->db->get('table')->result();

  $this->load->view('sampleView', $data); 
 }

}

3. So, call function library in your views.

foreach ($result as $row) {

echo $this->sample->debug($row->id) . “\n\n\n”;

}