如何使用Join定义JPA存储库查询？ [英] How to define JPA Repository Query with a Join?

问题描述

我想通过注释@Query创建一个Jpa存储库的Join查询我有三个表。

I would like to make a Join query by Jpa repository by annotation @Query I have three tables.

本机查询是：

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Table Hibernate实体，所以我尝试了ApplicationRepository

Now I have Table Hibernate entity, so I tried in ApplicationRepository

@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);

日志显示

意外令牌

unexpected token

有任何想法吗？

我的表实体

Application.java：

Application.java:

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

Customer.java ：

Customer.java:

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

User.java ：

User.java:

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

推荐答案

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

You don't need ON clauses in JPA, because the JPA already know how entities are associated thanks to the mapping annotations.

此外，您选择应用程序，这不是查询中定义的别名。

Moreover, you're selecting application, which is not an alias defined in your query.

你的联接毫无意义。

查询应该只是

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

阅读Hibernate文档以了解HQL和联接的工作原理。

Read the Hibernate documentation to understand how HQL and joins work.

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