How to Iterate Through an Array Multiple Times After Migrating from MySQL to PDO?

Moving from MySQL to PDO: Preserving Array Pointer

PDO offers a different approach to fetching data compared to MySQL's mysql_data_seek() method. To effectively iterate through an array multiple times, follow these steps:

Save Results to an Array:

Instead of relying on the PDO statement directly, save the results to an array using the fetchAll() method. This allows you to work with the array in a more controlled manner.

Code:

<code class="php">$pdo = new PDO('mysql:host=' . $host . ';dbname='.$database, $username, $password);
$pdo->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);

$stmt = $pdo->prepare('SELECT * FROM mytable WHERE active = 1 ORDER BY name ASC');
$stmt->setFetchMode(PDO::FETCH_ASSOC);
$stmt->execute();

$rows = $stmt->fetchAll();</code>

Iterate with Foreach Loop:

Now, you can iterate through the array as many times as needed using foreach loops. This approach enables you to start each iteration from the first element in the array.

Code:

<code class="php">foreach ($rows as $r) {
    // First iteration
}

foreach ($rows as $r) {
    // Second iteration
}</code>

Example:

Suppose you have an array of names stored in $rows. The following code demonstrates how to iterate through it twice:

<code class="php">foreach ($rows as $name) {
    echo $name . "<br>"; // First run: Display all names vertically
}

foreach ($rows as $name) {
    echo $name . " "; // Second run: Display all names horizontally
}</code>

Advantages:

• Allows for multiple iterations through the same data set
• Preserves array ordering and provides a stable starting point for each iteration
• Improves code readability and maintainability

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