JPA CRITERIA查詢通過加入列的順序

Question

如何通過對聯合實體調用訂單？我試圖實現與以下內容：

SELECT * FROM人員P內的p.id加入電話T = t.person_id通過s.name DESC加入上s.id = t.sim_id爲了SIM小號

@Entity 
public class Person implements Serializable{ 
    @Id 
    private Long id; 
    @OneToMany(orphanRemoval = true, mappedBy = "person", fetch = FetchType.LAZY, cascade = CascadeType.PERSIST) 
    private List<Telephone> telephonesNumber; 

@Entity 
public class Telephone implements Serializable { 
    @Id 
    private String number; 
    @Id 
    @ManyToOne() 
    @JoinColumn(name = "person_id") 
    private Person person; 
    @Id 
    @ManyToOne(cascade = {}) 
    @JoinColumn(name = "sim_id") 
    private Sim sim; 

@Entity 
public class Sim implements Serializable { 
    @Id 
    private Long id; 
    @Column(unique = true) 
    private String name; 

我用規範的接口，在這個例子中排序在場上person.id和它的作品

public class PersonSpecification implements Specification<Person> { 

    @Override 
    public Predicate toPredicate(Root<Person> root, CriteriaQuery<?> query, CriteriaBuilder builder) { 
     List<Predicate> predicates = new ArrayList<>(); 
// there is many different conditions for example 
//  if(someCondition!=null) { 
//   predicates.add(builder.like(root.get("someProperty"), someValue)); 
//  } 


     query.groupBy(root.get("id")); 
     //there I want to order by Sim.name i dont know how 
     query.orderBy(builder.asc(root.get("phone")));//this works 
     return builder.and((predicates.toArray(new Predicate[predicates.size()]))); 
    } 

我想Sim.name訂購，但我不知道怎麼辦。

Answer 1

在JPA規範，您可以使用：

query.orderBy(builder.asc(root.join("telephonesNumber").get("sim").get("name"))); 

通過SIM卡名稱進行排序。

有關詳細信息： https://en.wikibooks.org/wiki/Java_Persistence/Querying#Joining.2C_querying_on_a_OneToMany_relationship

如果您在使用JPA查詢：

@Query("select s from Person p 
     join p.telephonesNumber t 
     join t.sim s order 
     by t.sim.id desc") 

它會產生這樣的：

select * from person p 
inner join telephone t on p.id=t.person_id 
inner join sim s on t.sim_id=s.id 
order by t.sim_id desc 

有關詳細信息：

https://github.com/abhilekhsingh041992/spring-boot-samples/blob/master/jpa/src/main/java/example/springboot/jpa/repository/PersonRepository.java