如何用联接定义JPA存储库查询？

Question

本机查询为：

select application.APP_ID 
from user, customer, application 
where user.USE_CUSTOMER_ID = customer.CUS_ID 
and application.APP_CUSTOMER_ID = customer.CUS_ID 
and user.USE_ID=1;

现在我有了表Hibernate实体，所以我在ApplicationRepository中尝试了

@Query(SELECT  application FROM  Application a
  INNER JOIN customer c ON c.customer.id = a.customer.id 
  INNER JOIN user u ON u.customer.id = c.customer.id
  INNER JOIN application a ON a.user.id = u.id
  WHERE
  u.id = :user.id)
List<Application> findApplicationsByUser(@Param("User") User user);

日志上说

@Entity
@Table
public class Application extends BaseSimpleEntity {
...
    @ManyToOne(optional = false)
    private Customer customer;
...
}

@Entity
@Table
public class Customer extends BaseSimpleEntity {
...
    @OneToMany(mappedBy = "customer")
    private List<User> users;
    @OneToMany(mappedBy = "customer")
    private List<Application> applications;
...
}

@Entity
@Table
public class User extends BaseSimpleEntity {
...
    @ManyToOne(optional = false)
    private Customer customer;
...
}

Answer 1

在JPA中不需要ON子句，因为JPA已经知道实体是如何关联的，这要归功于映射注释。

此外，您选择的是application，它不是查询中定义的别名。

你的加入毫无意义。

select application FROM Application a
join a.customer c 
join c.users u
where u.id = :userId