for($i = 1; $i++){
        if(isset($_GET["filtr"])){
            switch($_GET["filtr"]){
                case "jmeno": 
                    $dotaz[$i] = "SELECT * FROM zakaznici ORDER BY jmeno"; 
                    break;
                case "id": 
                    $dotaz[$i] = "SELECT * FROM zakaznici ORDER BY id"; 
                    break;
            }
        } else {
            $dotaz[$i] = $dotaz1 = "SELECT * FROM zakaznici ORDER BY id";  
        }    

        $result[$i] = $pdo
                    ->query($dotaz[$i])
                    ->fetchAll();
       
    }