Symfony使用外键查询数据库

// 定义实体
namespace App\Entity;

use Doctrine\ORM\Mapping as ORM;

/**
 * @ORM\Entity
 * @ORM\Table(name="orders")
 */
class Order
{
    // ...
    
    /**
     * @ORM\ManyToOne(targetEntity="App\Entity\Customer")
     * @ORM\JoinColumn(name="customer_id", referencedColumnName="id")
     */
    private $customer;
    
    // ...
}

/**
 * @ORM\Entity
 * @ORM\Table(name="customers")
 */
class Customer
{
    // ...
    
    /**
     * @ORM\OneToMany(targetEntity="App\Entity\Order", mappedBy="customer")
     */
    private $orders;
    
    // ...
}

use Doctrine\ORM\EntityManagerInterface;

class OrderRepository
{
    private $entityManager;
    
    public function __construct(EntityManagerInterface $entityManager)
    {
        $this->entityManager = $entityManager;
    }
    
    public function findOrdersWithCustomers()
    {
        $queryBuilder = $this->entityManager->createQueryBuilder();
        
        $query = $queryBuilder->select('o', 'c')
            ->from(Order::class, 'o')
            ->join('o.customer', 'c')
            ->getQuery();
        
        return $query->getResult();
    }
}