Ouvrir une connexion d'une base de données en pph

try
{
$bdd = new PDO('mysql:host=hote;dbname=nomdelabase', 'pseudo', 'pass');
}
catch (PDOException $e)
{
die('Erreur: ' . $e->getMessage());
}

$req = $bdd->prepare('UPDATE comptes SET pseudo = :pseudo');
$req->execute(array('pseudo' => $variableavecpseudo));

require_once("mesfonctions/connexionbdd.php");

$req = $bdd->prepare('UPDATE nomdelatable SET colonne = :colonne');
$req->execute(array('colonne' => $variableamettrededans));

$req = $bdd->prepare('UPDATE nomdelatable SET colonne = :colonne WHERE id = :id');
$req->execute(array('colonne' => $variableamettrededans, 'id' => $iddelaligne));

$req = $bdd->query('SELECT * FROM table1 WHERE id = 1');

$donnees = $req->fetch();

echo $donnees['titre'];

$req = $bdd->prepare('UPDATE comptes SET pseudo = :pseudo');
$req->execute(array('pseudo' => $variableavecpseudo));

bdd = new PDO('mysql:host=localhost;dbname=nomdemabase', 'root', '');

SELECT * FROM table1
WHERE table1.id = 1

$req = $bdd->query("SELECT att1, att2 FROM table1 WHERE att2 like %".$_GET['valeur']."%");
$donnees = $req->fetch();
echo $donnees['att1'];
echo $donnees['att2'];

= $req = $bdd->query("SELECT att1, att2 FROM table1 WHERE att2 like %'.$_GET['valeur'].'%");

$recherche = '%' . $_GET['valeur'] . '%';
$req = $bdd->prepare("SELECT att1, att2 FROM table1 WHERE att2 like :recherche");
$req->execute(array('recherche' => $recherche));
$donnees = $req->fetch();
echo $donnees['att1'];
echo $donnees['att2'];

$recherche = '%' . $_GET['valeur'] . '%';
$req = $bdd->prepare("SELECT * FROM motrice WHERE att1 like :recherche");
$req->execute(array('recherche' => $recherche));
while($donnees = $req->fetch()){
      echo $donnees['att1'],'[separateur]', $donnees['att2'];
}

$req = $bdd->prepare("SELECT DISTINCT * FROM motrice WHERE att1 like :recherche");