Download file using - PHP

            $backup = "Your file data";

            $folder = 'assets/db/';

            if (!is_dir($folder))

                mkdir($folder, 0755, true);

            $date = date('m-d-Y-H-i-s', time());

            $file_name = "filename-" . $date . '.sql';

            $file_url = $folder . $file_name;

            $handle = fopen($file_url, 'w+');

            fwrite($handle, $backup);

            fclose($handle);

            header('Content-Type: application/octet-stream');

            header("Content-Transfer-Encoding: Binary");

            header("Content-disposition: attachment; filename=\"" . $file_name . "\"");

            readfile($file_url);