// Generated Repository Method
public interface UserRepository extends JpaRepository<User, Long> {
    List<User> findByActiveAndCreatedAtAfter(
        boolean active, 
        LocalDateTime date
    );
}

// Usage
@Service
public class UserService {
    @Autowired
    private UserRepository userRepository;
    
    public List<User> getRecentActiveUsers() {
        return userRepository.findByActiveAndCreatedAtAfter(
            true, 
            LocalDateTime.now().minusDays(30)
        );
    }
}

// Generated JPQL Query
@Query("""
    SELECT DISTINCT o FROM Order o
    JOIN FETCH o.orderItems i
    JOIN FETCH o.customer c
    WHERE (SELECT SUM(oi.price * oi.quantity) 
           FROM OrderItem oi 
           WHERE oi.order = o) > 100
    ORDER BY o.createdAt DESC
""")
List<Order> findOrdersWithItemsAndCustomer();

// Generated Criteria API Query
public List<Product> findLowStockHighDemandProducts(LocalDateTime since, int threshold) {
    CriteriaBuilder cb = entityManager.getCriteriaBuilder();
    CriteriaQuery<Product> cq = cb.createQuery(Product.class);
    Root<Product> product = cq.from(Product.class);
    Join<Product, Inventory> inventory = product.join("inventory", JoinType.LEFT);
    Subquery<Long> demandCount = cq.subquery(Long.class);
    Root<OrderItem> orderItem = demandCount.from(OrderItem.class);

    demandCount.select(cb.count(orderItem))
        .where(cb.equal(orderItem.get("product"), product),
               cb.greaterThanOrEqualTo(orderItem.get("createdAt"), since));
    
    cq.select(product)
        .where(cb.and(
            cb.lessThanOrEqualTo(inventory.get("stockLevel"), inventory.get("reorderPoint")),
            cb.greaterThanOrEqualTo(demandCount, threshold)
        ));
    
    return entityManager.createQuery(cq).getResultList();
}

@Query("""
    SELECT new com.example.dto.SalesReport(
        FUNCTION('DATE_FORMAT', o.createdAt, '%Y-%m') as month,
        SUM(o.totalAmount) as revenue,
        COUNT(o) as orderCount
    )
    FROM Order o
    WHERE o.createdAt >= :startDate
    GROUP BY month
    ORDER BY month DESC
""")
List<SalesReport> getMonthlySalesReport(LocalDateTime startDate);

// Specification for dynamic filtering
public class OrderSpecifications {
    public static Specification<Order> withDynamicCriteria(
            LocalDateTime startDate,
            LocalDateTime endDate,
            String status,
            BigDecimal minAmount) {
        
        return (root, query, cb) -> {
            List<Predicate> predicates = new ArrayList<>();
            
            if (startDate != null && endDate != null) {
                predicates.add(cb.between(
                    root.get("createdAt"), 
                    startDate, 
                    endDate
                ));
            }
            
            if (status != null) {
                predicates.add(cb.equal(
                    root.get("status"), 
                    OrderStatus.valueOf(status)
                ));
            }
            
            if (minAmount != null) {
                predicates.add(cb.greaterThanOrEqualTo(
                    root.get("totalAmount"), 
                    minAmount
                ));
            }
            
            return cb.and(predicates.toArray(new Predicate[0]));
        };
    }
}