public function __construct(mysqli $connection, $charset = 'utf8')
{
$this->connection = $connection;
if ($connection->connect_errno) {
throw new Exception($connection->connect_error);
} elseif (!$connection->set_charset($charset)) {
// was added in MySQL 5.0.7 and PHP 5.0.5, fixed in PHP 5.1.5)
throw new Exception($connection->error);
}
}