function signature($id){
    global $connection;
    $query = "SELECT a.* FROM admin_files a LEFT JOIN support_files s ON s.admin_file_id = a.id AND s.support_id='$id' WHERE s.admin_file_id IS NULL AND a.signature= 1";
    $res = mysqli_query($connection, $query);
        $signature = array();
        while($row = mysqli_fetch_assoc($res)){
            $signature[$row['id']] = $row;
        }
        return $signature;
}