Spring Boot Tutorial 0/110 lessons ~6 min read Lesson 31“Production-grade backends”

JPQL

JPQL (Java Persistence Query Language) looks like SQL but operates on entities and fields, not tables and columns.

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Focus

3 guided sections

Practice signal

Examples included

Career prep

Foundation builder

Introduction

JPQL (Java Persistence Query Language) looks like SQL but operates on entities and fields, not tables and columns. It's portable across DBs and integrates cleanly with Spring Data @Query.

Informative example

public interface OrderRepository extends JpaRepository<Order, Long> {

  @Query("""
      select o from Order o
      join fetch o.items i              -- avoid N+1
      where o.userId = :userId
        and o.status in :statuses
      order by o.createdAt desc
      """)
  List<Order> findFor(@Param("userId") Long userId,
                      @Param("statuses") Collection<OrderStatus> statuses);

  @Modifying
  @Query("update Order o set o.status = :status where o.id = :id")
  int updateStatus(@Param("id") Long id, @Param("status") OrderStatus status);
}

Best practices

Use join fetch to eliminate N+1 on collections you read together.
@Modifying + @Transactional for bulk updates/deletes.
JPQL > native SQL when portability matters; native SQL > JPQL when DB-specific features matter.

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