Migrate PHP MySQL to PDO for Secure Database Access
Description
Older PHP apps often use mysql_* functions which are deprecated. Upgrading to PDO ensures security with prepared statements and supports multiple databases.
Original Code (Outdated)
$conn = mysql_connect("localhost", "user", "pass");
mysql_select_db("mydb", $conn);
$result = mysql_query("SELECT * FROM users");
Updated Code (Modern)
$pdo = new PDO("mysql:host=localhost;dbname=mydb", "user", "pass");
$stmt = $pdo->query("SELECT * FROM users");
$result = $stmt->fetchAll();