$DB_HOST ='IP';
$DB_PRE ='Prefijo DB';
$dbUsing ='Base de datos a usar';
$DB_USERNAME='Nombre Usuario';
$DB_PASS='Contraseña';

$conn    = new PDO("mysql:host=" . $DB_HOST . ";dbname=" . $DB_PRE . "" . $dbUsing . "", $DB_USERNAME, $DB_PASS);
$conn->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
$conn->beginTransaction();
$conn->exec("set names utf8");
$conn->exec($stmt);
$conn->commit();