try {
            $dsn = "mysql:host={$config['DB_HOST']};port={$config['DB_PORT']};dbname={$config['DB_DATABASE']};charset=utf8mb4";
            
            $options = [
                PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION,
                PDO::ATTR_DEFAULT_FETCH_MODE => PDO::FETCH_ASSOC,
                PDO::ATTR_EMULATE_PREPARES => false,
                PDO::MYSQL_ATTR_INIT_COMMAND => "SET NAMES utf8mb4 COLLATE utf8mb4_unicode_ci"
            ];
            
            $this->connection = new PDO($dsn, $config['DB_USERNAME'], $config['DB_PASSWORD'], $options);
            
        } catch (PDOException $e) {
            error_log("Database Connection Error: " . $e->getMessage());
            die("Database connection failed. Please check your configuration.");
        }
    }
    
    /**
     * Get singleton instance
     */
    public static function getInstance() {
        if (self::$instance === null) {
            self::$instance = new self();
        }
        return self::$instance;
    }
    
    /**
     * Get PDO connection
     */
    public function getConnection() {
        return $this->connection;
    }
    
    /**
     * Prepare and execute query
     */
    public function query($sql, $params = []) {
        try {
            $stmt = $this->connection->prepare($sql);
            $stmt->execute($params);
            return $stmt;
        } catch (PDOException $e) {
            error_log("Query Error: " . $e->getMessage());
            throw $e;
        }
    }
    
    /**
     * Fetch all results
     */
    public function fetchAll($sql, $params = []) {
        $stmt = $this->query($sql, $params);
        return $stmt->fetchAll();
    }
    
    /**
     * Fetch single result
     */
    public function fetchOne($sql, $params = []) {
        $stmt = $this->query($sql, $params);
        return $stmt->fetch();
    }
    
    /**
     * Insert record and return last insert ID
     */
    public function insert($sql, $params = []) {
        $this->query($sql, $params);
        return $this->connection->lastInsertId();
    }
    
    /**
     * Update record and return affected rows
     */
    public function update($sql, $params = []) {
        $stmt = $this->query($sql, $params);
        return $stmt->rowCount();
    }
    
    /**
     * Delete record and return affected rows
     */
    public function delete($sql, $params = []) {
        $stmt = $this->query($sql, $params);
        return $stmt->rowCount();
    }
    
    /**
     * Begin transaction
     */
    public function beginTransaction() {
        return $this->connection->beginTransaction();
    }
    
    /**
     * Commit transaction
     */
    public function commit() {
        return $this->connection->commit();
    }
    
    /**
     * Rollback transaction
     */
    public function rollback() {
        return $this->connection->rollBack();
    }
    
    /**
     * Prevent cloning
     */
    private function __clone() {}
    
    /**
     * Prevent unserialization
     */
    public function __wakeup() {
        throw new Exception("Cannot unserialize singleton");
    }
}
<br />
<b>Fatal error</b>:  Uncaught Error: Class &quot;Database&quot; not found in H:\Other computers\My MacBook Pro\htdocs\sada1\src\Models\Merchant.php:13
Stack trace:
#0 H:\Other computers\My MacBook Pro\htdocs\sada1\src\Controllers\AuthController.php(19): Merchant-&gt;__construct()
#1 H:\Other computers\My MacBook Pro\htdocs\sada1\src\Helpers\Router.php(133): Controllers\AuthController-&gt;__construct()
#2 H:\Other computers\My MacBook Pro\htdocs\sada1\src\Helpers\Router.php(86): Router::callControllerAction('AuthController@...', Array)
#3 H:\Other computers\My MacBook Pro\htdocs\sada1\public\routes.php(57): Router::dispatch()
#4 H:\Other computers\My MacBook Pro\htdocs\sada1\public\index.php(45): require_once('H:\\Other comput...')
#5 {main}
  thrown in <b>H:\Other computers\My MacBook Pro\htdocs\sada1\src\Models\Merchant.php</b> on line <b>13</b><br />