如何通过加入的实体调用订单?我试图通过以下方式实现以下目标:
select * from person p inner join telephone t on p.id = t.person_id join s s on s.id = t.sim_id order by s.name DESC
@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;
我使用规范界面,在这个例子中,排序是在字段person.id上,它的工作原理
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()])));
}
我想通过Sim.name订购,但我不知道如何 .
1 回答
在JPA规范中,您可以使用:
按sim名称排序 .
有关详细信息:https://en.wikibooks.org/wiki/Java_Persistence/Querying#Joining.2C_querying_on_a_OneToMany_relationship
如果您使用JPA查询:
它会产生这个:
更多细节:
https://github.com/abhilekhsingh041992/spring-boot-samples/blob/master/jpa/src/main/java/example/springboot/jpa/repository/PersonRepository.java