MySQL Update

$stmt = $pdo->prepare(
    'UPDATE customers SET email = ? WHERE id = ?'
);
$stmt->execute(['new@example.com', 42]);

echo $stmt->rowCount();   // 1 if found and changed, 0 otherwise

$stmt = $pdo->prepare(
    'UPDATE customers SET name = ?, email = ?, updated_at = NOW() WHERE id = ?'
);
$stmt->execute(['Ada Lovelace', 'ada@example.com', 42]);

$pdo->prepare(
    'UPDATE products SET stock = stock - 1 WHERE id = ? AND stock > 0'
)->execute([$productId]);
// the "AND stock > 0" stops the stock from going negative

$pdo->exec(
    "UPDATE customers SET active = 0 WHERE last_login < NOW() - INTERVAL 1 YEAR"
);

// ✗ Race: two requests both read stock=5, both write 4
$row = $pdo->query('SELECT stock FROM products WHERE id=42')->fetch();
$pdo->exec('UPDATE products SET stock = ' . ($row['stock'] - 1) . ' WHERE id = 42');

// ✓ Atomic — the DB handles concurrency
$pdo->prepare('UPDATE products SET stock = stock - 1 WHERE id = ? AND stock > 0')
    ->execute([42]);

$stmt = $pdo->prepare(
    'UPDATE customers SET email = ?, version = version + 1
     WHERE id = ? AND version = ?'
);
$stmt->execute([$newEmail, $id, $oldVersion]);

if ($stmt->rowCount() === 0) {
    throw new ConcurrencyException('Customer changed since you opened the form.');
}

<?php
$stmt = $pdo->prepare('UPDATE customers SET email = ? WHERE id = ?');
$stmt->execute(['new@example.com', 42]);