class Post{
    private $pdo;

    public function __construct(){
        $this->connect();
    }

    public function connect(){
        try {
            $this->pdo = new PDO('mysql:host=localhost;dbname=veritabaniveritabani;charset=utf8', 'kullaniciAdi', 'sifre');
            $this->pdo->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
            $this->pdo->query('SET NAMES utf8');
        }catch (PDOException $e) {
            echo 'Veritabanı bağlantısı başarısız oldu: ' . $e->getMessage();
        }
    }

    public function onceki($id){
        $sql = 'SELECT * FROM Tablo WHERE id < ? ORDER BY id DESC LIMIT 1';
        $query = $this->pdo->prepare($sql);
        $query->execute(array($id));
        return $query->fetch();
    }

    public function sonraki($id){
        $sql = 'SELECT * FROM Tablo WHERE id > ? ORDER BY id ASC LIMIT 1';
        $query = $this->pdo->prepare($sql);
        $query->execute(array($id));
        return $query->fetch();
    }
}

$class = new Post();

class Post extends CI_Model{

    function onceki($id){
        $this->db->select("*");
        $this->db->from("tablo");
        $this->db->where("id < " . $id);
        $this->db->order_by("id","desc");
        $this->db->limit(1);
        return $this->db->get()->row_array();
    }

    function sonraki($id){
        $this->db->select("*");
        $this->db->from("tablo");
        $this->db->where("id > " . $id);
        $this->db->order_by("id","asc");
        $this->db->limit(1);
        return $this->db->get()->row_array();
    }

}