config.php

<?php
define('DB_HOST', '127.127.126.25');
define('DB_USER', 'root');
define('DB_PASS', '');
define('DB_NAME', 'transactions_app');

class Database {
    private static $instance = null;
    private $connection;

    private function __construct() {
        try {
            $this->connection = new PDO(
                "mysql:host=" . DB_HOST . ";dbname=" . DB_NAME,
                DB_USER,
                DB_PASS
            );
            $this->connection->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
        } catch(PDOException $e) {
            die("Connection failed: " . $e->getMessage());
        }
    }

    public static function getInstance() {
        if (self::$instance == null) {
            self::$instance = new Database();
        }
        return self::$instance;
    }

    public function getConnection() {
        return $this->connection;
    }
}