// Require Composer's autoload file require_once __DIR__ . '/vendor/autoload.php'; use Doctrine\ORM\EntityManager; use Doctrine\ORM\Tools\Setup; $config = Setup::createAnnotationMetadataConfiguration( array(__DIR__ . '/src/App/Entity'), true ); $entityManager = EntityManager::create( array( 'driver' => 'pdo_mysql', 'user' => 'root', 'password' => '', 'dbname' => 'test_db' ), $config );In this example, we are creating an EntityManager object that connects to a MySQL database using PDO. We are also using Doctrine's AnnotationMetadataConfiguration to automatically map our entity classes to database tables based on their annotations. Package library: Doctrine ORM. Overall, Doctrine is a powerful ORM tool that simplifies database access and management for PHP developers. Its autoloading feature makes it easy to use in any project, and it supports a wide range of database platforms and configuration options.