如何将此代码从mysqli更改为PDO

Question

if (isset($_GET['page_no']) && $_GET['page_no']!="") {
    $page_no = $_GET['page_no'];
    } else {
        $page_no = 1;
        }

    $total_records_per_page = 9;
    $offset = ($page_no-1) * $total_records_per_page;
    $previous_page = $page_no - 1;
    $next_page = $page_no + 1;
    $adjacents = "2"; 

    $result_count = mysqli_query($con,"SELECT COUNT(*) As total_records FROM `products`");
    $total_records = mysqli_fetch_array($result_count);
    $total_records = $total_records['total_records'];
    $total_no_of_pages = ceil($total_records / $total_records_per_page);
    $second_last = $total_no_of_pages - 1; // total page minus 1

    $result = mysqli_query($con,"SELECT * FROM `products` LIMIT $offset, $total_records_per_page");
    while($row = mysqli_fetch_array($result)){
        echo "<tr>
              <td>".$row['productCode']."</td>
              <td>".$row['productName']."</td>
              <td>".$row['MSRP']."</td>
              <td><button type='submit' class='buy'>Buy Now</button></td>
              </tr>";
        }
    mysqli_close($con);
    ?>

I need to change this code to PDO format. And I am not really sure what is the same function of mysqli_fetch_array in PDO.

Answer 1

This is how you would do it:

// Execute query and fetch a single cell from the result
$total_records = $PDO->query('SELECT COUNT(*) FROM `products`')->fetch(PDO::FETCH_COLUMN);

$total_no_of_pages = ceil($total_records / $total_records_per_page);
$second_last = $total_no_of_pages - 1; // total page minus 1

// prepare a statement with 2 parameters and execute it
$stmt = $PDO->prepare('SELECT * FROM `products` LIMIT ?,?');
$stmt->execute([$offset, $total_records_per_page]);
// PDO results are easily traversable
foreach ($stmt->fetchAll() as $row) {
    echo "<tr>
        <td>".$row['productCode']."</td>
        <td>".$row['productName']."</td>
        <td>".$row['MSRP']."</td>
        <td><button type='submit' class='buy'>Buy Now</button></td>
        </tr>";
}

I replaced your concatenated query with a prepared statement, which you should always do!

About fetching: You can traverse the records one by one or fetch all of them like I did into an array and foreach on them. There is many different ways to do it. Always remember about many PDO fetch options available: https://phpdelusions.net/pdo#fetchall