class DB extends PDO {
    public $echo_in_log = true;

    public function __construct($dsn, $username = null, $password = null) {
        try {
            parent::__construct($dsn, $username, $password);
            $this->exec("SET NAMES 'utf8'");
            //$db->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
        } catch (PDOException $e) {
            in_log('DB connect error');
        }
    }

    public function ex($sql, array $params = null) {
        $res = null;
        if (!($res = $this->prepare($sql)) ||
            !$res->execute($params)
        ) in_log('DB error. Sql:'.$sql."\nParams".print_r($params, 1));
        return $res;
    }

    protected function in_log($mess) {
        if ($this->echo_in_log) echo 'error';
        in_log($mess);
    }
}