Connection::__construct

public Connection::__construct(\PDO $connection, array $connection_options = array())

public function __construct(\PDO $connection, array $connection_options = array()) {
  parent::__construct($connection, $connection_options);

  // This driver defaults to transaction support, except if explicitly passed FALSE.
  $this->transactionSupport = !isset($connection_options['transactions']) || ($connection_options['transactions'] !== FALSE);

  // MySQL never supports transactional DDL.
  $this->transactionalDDLSupport = FALSE;

  $this->connectionOptions = $connection_options;
}