PDO + singleton

	class connexion_serveur {

           /**
	     * instance de la classe pdo
	     */
	    private $pdoinstance = null;

	    /**
	     * instance de la classe spdo
	     */
	    private static $instance = null;
 
	    private function __construct()	    {
	        try {
	        $this->pdoinstance = new pdo(db_dsn, db_user, db_password);
	        $this->pdoinstance->query("set names utf8");//for using utf-8
	        $this->pdoinstance->query("set character set 'utf8'");//for using utf-8
	        }
	        catch (pdoexception $e){
	            echo 'erreur : '.$e->getmessage().'<br>';
	            die();
	        }
	        
	    }
 
	    /**
	     * crée et retourne l'objet spdo
	     */
	    public static function getinstance()
	    {
	        if(is_null(self::$instance)or !isset(self::$instance))      {
	            self::$instance = new connexion_serveur();
	        }
	        return self::$instance;
	    }
        /**
        * empeche la copie externe de l'instance
        */
	    private function __clone() {
	        throw new exception('le clonage de spdo n\'est pas autoris&eacute;');
	    }
	}

$db=connexion_serveur::getinstance();
$insert = "insert into logs_erreurs (date_erreur, texte_erreur) values (?, ?)";
$statement = $db->prepare($insert);
$statement->bindparam(1, "test", pdo::param_str);
$statement->bindparam(2, "texte", pdo::param_str);
$statement->execute();

public static function getinstance() {
  null === self::$instance or self::$instance = new self();
  return self::$instance;
}

public static function getinstance() {
  if (null === self::$instance) {
    self::$instance = new self();
  }
  return self::$instance;
}

connexion_serveur::getinstance() -> query('select nom from table') -> fetchobj() -> nom;

$db = connexion_serveur::getinstance();
$db -> prepare('select login, password from users where login=:login limit 1');
$db -> bindvalue(':login', $_post['login'], pdo::param_str);
$db -> execute();

class connexion_serveur extends pdo {
  public function __construct() {
    parent::__construct($dsn, $username, $password);
  }
}

class connexion_serveur extends pdo {
  public function __construct() {
    parent::__construct($dsn, $username, $password);
 try {
	        $this->pdoinstance = new pdo(db_dsn, db_user, db_password);
	        $this->pdoinstance->query("set names utf8");//for using utf-8
	        $this->pdoinstance->query("set character set 'utf8'");//for using utf-8
	        }
	        catch (pdoexception $e){
	            echo 'erreur : '.$e->getmessage().'<br>';
	            die();
	        }
  }
}

class pdo {

        	    /**
	     * instance de la classe pdo
	     */
	    private $pdoinstance = null;

	    /**
	     * instance de la classe spdo
	     */
	    private static $instance = null;

	    private function __construct()	    {
	
	 
	
	    }

	    /**
	     * crée et retourne l'objet spdo
	     */
	    public static function getinstance()
	    {
	        if(null === self::$instance or !isset(self::$instance))      {
	            self::$instance = new self();
	        }
	        return self::$instance;
	    }
        /**
        * empeche la copie externe de l'instance
        */
	    private function __clone() {
	        throw new exception('le clonage de spdo n\'est pas autorisé');
	    }
	}

$db = connexion_serveur::getinstance();
$db -> prepare('select login, password from users where login=:login limit 1');
$db -> bindvalue(':login', $_post['login'], pdo::param_str);
$db -> execute();

class pdo {
	public function __construct()	    {
			try {
	        $this->PDOInstance = new PDO(DB_SESSIONS_DSN, DB_SESSIONS_USER, DB_SESSIONS_PASSWORD);
	        $this->PDOInstance->query("SET NAMES utf8");//FOR USING UTF-8
	        $this->PDOInstance->query("SET CHARACTER SET 'utf8'");//FOR USING UTF-8
	        }
	        catch (PDOException $e){
	            echo 'Erreur : '.$e->getMessage().'<br>';
	            die();
	        }
	}

}
	class Connexion_serveur extends pdo{



	    /** Instance de la classe SPDO */
	    private static $instance = null;

	    private function __construct()	    {
			parent::__construct();
	    }

	    /** Crée et retourne l'objet SPDO   */
	    public static function getInstance()
	    {
	        if(null === self::$instance OR !ISSET(self::$instance))      {
	            self::$instance = new self();
	        }
	        return self::$instance;
	    }
        /**Empeche la copie externe de l'instance */
	    private function __clone() {
	        throw new Exception('Le clonage de SPDO n\'est pas autoris&eacute;');
	    }
	}

$db=Connexion_serveur::getInstance();
$insert = "INSERT INTO logs_erreurs (date_erreur, texte_erreur) VALUES (?, ?)";
$statement = $db->prepare($insert);

$statement->bindParam(1, "test", PDO::PARAM_STR);
$statement->bindParam(2, "texte", PDO::PARAM_STR);
$statement->execute();

  try {$this->PDOInstance = new PDO(DB_SESSIONS_DSN, DB_SESSIONS_USER, DB_SESSIONS_PASSWORD);
  $this->PDOInstance->query("SET NAMES utf8");//FOR USING UTF-8
  $this->PDOInstance->query("SET CHARACTER SET 'utf8'");//FOR USING UTF-8
}
catch (PDOException $e){
  echo 'Erreur : '.$e->getMessage().'<br>';
  die();
}

  public function __construct($dsn, $username, $password) {
    parent::__construct($dsn, $username, $password);
    $this -> query("SET NAMES utf8");
    $this -> query("SET CHARACTER SET 'utf8'");
  }