Скачивание информации с html страницы

<?php   
    session_start();
    include_once('db.php');
    if(isset($_SESSION['userid'])){
        $sesion_id=$_SESSION['userid'];
        $result = $mysqli->query("SELECT * FROM `user` where id=$sesion_id");
        $row = $result->fetch_assoc(); 
 
        $result2 = $mysqli->query("SELECT * FROM `user_prefs` where id=$sesion_id");
        $user_prefs_row = $result2->fetch_assoc();
 
        $validsql=$mysqli->query("SELECT * FROM `wallets` WHERE id='".$sesion_id."'");
        $valid_row = $validsql->fetch_assoc();
    }
    else{
        header("Location:");
        exit;
    }
 if(isset( $_POST['btnexp'] ) )
    {
$check = $mysqli->query("SELECT * FROM `trade_history`  where $sesion_id=ID_prod");
    $results = array();
 
    while ($row = $check->fetch_assoc())
    {
        $results[] = $row['Val'] . ',' . $row['Prod'];
    }
 
    $content = join($results, "\n"); 
    $result->free();
 
    header("Content-Type: text/csv");
    header("Content-Disposition: attachment;filename=myfilename.csv");
    echo $content;
    }
?>

if(isset( $_POST['btnexp'] ) )
    {
$check = $mysqli->query("SELECT * FROM `trade_history`  where $sesion_id=ID_prod");
    $results = array();
 
    while ($row = $check->fetch_assoc())
    {
        $results[] = $row['Val'] . ',' . $row['Prod'];
    }
 
    $content = join($results, "\n"); 
    $result->free();
 
    header("Content-Type: text/csv");
    header("Content-Disposition: attachment;filename=myfilename.csv");
    echo $content;
    }