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PDO Database Access

7 min read Quiz at the end

PDO is the recommended way to connect PHP to databases securely. Always use prepared statements with named placeholders like :email to prevent SQL injection. PDO works with MySQL, PostgreSQL, SQLite, and more.

PDO — PHP Data Objects

// Connect
$pdo = new PDO(
    "mysql:host=localhost;dbname=shop;charset=utf8mb4",
    "user",
    "password",
    [
        PDO::ATTR_ERRMODE            => PDO::ERRMODE_EXCEPTION,
        PDO::ATTR_DEFAULT_FETCH_MODE => PDO::FETCH_ASSOC,
        PDO::ATTR_EMULATE_PREPARES   => false,
    ]
);

// SELECT with prepared statement (safe from SQL injection)
$stmt = $pdo->prepare("SELECT * FROM users WHERE age > :age");
$stmt->execute(["age" => 18]);
$users = $stmt->fetchAll();

// INSERT
$stmt = $pdo->prepare(
    "INSERT INTO users (name, email) VALUES (:name, :email)"
);
$stmt->execute(["name" => "Alice", "email" => "a@b.com"]);
$newId = $pdo->lastInsertId();

// Transaction
$pdo->beginTransaction();
try {
    $pdo->prepare("UPDATE accounts SET balance=balance-? WHERE id=?")->execute([100, 1]);
    $pdo->prepare("UPDATE accounts SET balance=balance+? WHERE id=?")->execute([100, 2]);
    $pdo->commit();
} catch (Exception $e) {
    $pdo->rollBack();
}

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Topic Quiz · 5 questions

Test your understanding before moving on

1. What does PDO stand for?

💡 PDO stands for PHP Data Objects — a database abstraction layer.

2. Why use prepared statements?

💡 Prepared statements separate SQL from data, preventing SQL injection.

3. Which PDO method runs a query and returns a statement?

💡 prepare() creates a prepared statement; execute() runs it.

4. Which fetch mode returns associative arrays?

💡 PDO::FETCH_ASSOC returns rows as associative arrays with column names as keys.

5. How do you start a transaction in PDO?

💡 $pdo->beginTransaction() starts a database transaction.

Quick Access

PDO Database Access

PDO — PHP Data Objects

Test your understanding before moving on