PDO - нужны ответы!

      $dsn = "mysql:host=$host;dbname=$db;charset=$charset";
      $opt = array(
           PDO::ATTR_ERRMODE            => PDO::ERRMODE_EXCEPTION,
           PDO::ATTR_DEFAULT_FETCH_MODE => PDO::FETCH_ASSOC
           );
         $pdo = new PDO($dsn, $user, $pass, $opt);

 $pdo = new PDO($dsn, $user, $pass, $opt);

$sql = 'SELECT name FROM users WHERE email = :email';

$stmt->execute(array('email' => $email));

$stmt = $pdo->prepare('SELECT name FROM users WHERE email = ?');

$stmt = $pdo->prepare('SELECT name FROM users WHERE email = ? AND id= ?');

$result =$pdo->query ("SELECT * FROM wp_posts_us  WHERE access='true'AND hot_to_gen='true' UNION SELECT * FROM wp_posts_job WHERE access='true' AND hot_to_gen='true' ORDER BY id DESC LIMIT 3");

session_start();
  $user = $_SESSION["email"];
  $favor = $db->prepare('SELECT * FROM wp_favourite WHERE user = ?'); //19 строка
  $favor->execute(array($user));

try {
  $db = new PDO("mysql:host=$host;dbname=$dbase", $user, $pass);
  $db->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
  $db->exec("set names utf8");
}
catch(PDOException $e) {
    echo $e->getMessage();
}

$host = 'ewartfghj';
 $dbase = 'poiug';
 $charset = 'utf-8';
 $user = 'ksdkfn';
 $pass = 'a3i4tosdf';
try {
  $db = new PDO("mysql:host=$host;dbname=$dbase", $user, $pass);
  $db->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
  $db->exec("set names utf8");
}
catch(PDOException $e) {
    echo $e->getMessage();
}
session_start();
  $user = $_SESSION["email"];
$favor = $db->prepare('SELECT * FROM wp_favourite WHERE user = ?');
$favor->execute(array($user));

var_dump($db);