<?php
define('DB_HOST', '127.0.0.1');
define('DB_NAME', 'app_db');
define('DB_USER', 'user');
define('DB_PASS', 'password');

function db() {
    try {
        $pdo = new PDO('mysql:host=' . DB_HOST . ';dbname=' . DB_NAME, DB_USER, DB_PASS);
        $pdo->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
        return $pdo;
    } catch (PDOException $e) {
        die('Connection failed: ' . $e->getMessage());
    }
}