从数据库中检索pdf blob数据

    $report_pdf = stripslashes($pdf_data);
    $pdf = new FPDF();
    $pdf->AddPage();
    $pdf->SetFont('Arial', '', 12);
    $pdf->MultiCell(190, 5, $report_pdf);
    $pdfcontent = $pdf->Output("", "S");
    $currentDate =date('y-m-d');
    $endDate = date('y-m-d', strtotime("+36 months"));

    $conn = mysqli_connect(DATABASE_HOST,DATABASE_USER,DATABASE_PASSWORD, DATABASE_NAME, DATABASE_PORT);
    // Check connection
    if (! $conn) {
        die("Connection failed: " . mysqli_connect_error());
    }

    $id = $_SESSION['userid'];
    $iban =  $_SESSION['iban'];
    $bic = $_SESSION['bic'];

    $sql = "INSERT INTO ".table." (userid, useriban, userbic,pdf, start, end )
        VALUES ($id, '$iban', '$bic', ?,'$currentDate', '$endDate')";

    if ($query  = $conn->prepare($sql)) 
    {
           $query->bind_param('s', $pdfcontent);
           $query->execute();                      
    }

    // To Retrieve PDF from DataBase
    $sql=$conn->prepare("SELECT pdf FROM sauberlux_com.tbl_b2csepa where id = 1");

    if(  $query = $conn->prepare($sql))
    {
        $query->execute();
        $query->store_result();
        $query->bind_result($pdfcontent);


        while($query->fetch())
        {
            header("Content-Length: " . strlen($pdfcontent) );
            header('Content-Type: application/octet-stream');
            header('Content-Disposition: attachment;filename=test.pdf');
            header("Content-Transfer-Encoding: binary
");
            echo $pdfcontent;

        }
    }

my code is working correctly to store pdf data as blob in database. but when i want to retrieve that data data from database that part of my code is not working. please any one help me. I have checked my query its selecting the correct data but i am not getting any output or anything.