transformer mysqli en pdo

<?php
//fetch.php
//require_once 'include/bdd.inc.php';
$connect = mysqli_connect("localhost", "root", "", "mysql");
$column = array("product.id", "product.name", "category.category_name", "product.price");
$query = "
 SELECT * FROM product 
 INNER JOIN category 
 ON category.category_id = product.category 
";
$query .= " WHERE ";
if(isset($_POST["is_category"]))
{
 $query .= "product.category = '".$_POST["is_category"]."' AND ";
}
if(isset($_POST["search"]["value"]))
{
 $query .= '(product.id LIKE "%'.$_POST["search"]["value"].'%" ';
 $query .= 'OR product.name LIKE "%'.$_POST["search"]["value"].'%" ';
 $query .= 'OR category.category_name LIKE "%'.$_POST["search"]["value"].'%" ';
 $query .= 'OR product.price LIKE "%'.$_POST["search"]["value"].'%") ';
}
if(isset($_POST["order"]))
{
 $query .= 'ORDER BY '.$column[$_POST['order']['0']['column']].' '.$_POST['order']['0']['dir'].' ';
}
else
{
 $query .= 'ORDER BY product.id DESC ';
}
$query1 = '';
if($_POST["length"] != 1)
{
 $query1 .= 'LIMIT ' . $_POST['start'] . ', ' . $_POST['length'];
}
$number_filter_row = mysqli_num_rows(mysqli_query($connect, $query));
$result = mysqli_query($connect, $query . $query1);
$data = array();
while($row = mysqli_fetch_array($result))
{
 $sub_array = array();
 $sub_array[] = $row["id"];
 $sub_array[] = $row["name"];
 $sub_array[] = $row["category_name"];
 $sub_array[] = $row["price"];
 $data[] = $sub_array;
}
function get_all_data($connect)
{
 $query = "SELECT * FROM product";
 $result = mysqli_query($connect, $query);
 return mysqli_num_rows($result);
}
$output = array(
 "draw"    => intval($_POST["draw"]),
 "recordsTotal"  =>  get_all_data($connect),
 "recordsFiltered" => $number_filter_row,
 "data"    => $data
);
echo json_encode($output);
?>

try {
       $bdd = new PDO('mysql:host=127.0.0.1;dbname=mysql', 'root', '');
        } catch(Exception $e) {
           echo 'Erreur: ', $e->getMessage(), "\n";
        }
   $bdd->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
   $bdd->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_WARNING);