JPA使用OneToMany

Question

我想使用@Query注释从具有@OneToMany关系的实体创建左连接查询。

父实体是：

    @Entity
    @Table(name="Registration")
    public class Registration {

       @Column(nullable = false)
       @Type(type = "org.jadira.usertype.dateandtime.joda.PersistentLocalDate")
       private LocalDate effect;

       @OneToMany(targetEntity=Payment.class, cascade=CascadeType.ALL,fetch = FetchType.LAZY)
       @JoinColumn(name="uuid")
       private List<Payment> payment;
   }

孩子：

    @Entity
    @Table(name="Payment")
    public class Payment {

       @Id
       @GeneratedValue(generator = "uuid")
       @GenericGenerator(name="uuid", strategy = "uuid2")
       @Column(columnDefinition = "BINARY(16)")
       private UUID uuid;
}

对于DAO，我喜欢以下内容：

@Query("SELECT p FROM Registration r JOIN r.payment p WHERE r.effect = :effect")
Iterable<Payment> find(@Param("effect") LocalDate effect);

显然，它的错误是因为生成的查询是：

  

选择payment1_.uuid作为uuid1_9_，payment1_.amount作为amount2_9_来自注册registrati0_内部加入付款payment1_ on registrati0_.uuid = payment1_.uuid where registrati0_.effect =？

生成关系表时

：

对我来说，正确的查询应该是这样的：

  

从注册r中选择p。*在rp.registration = r.uuid上加入registration_payment rp在p.uuid = rp.payment上加入付款p其中r.effect =＆＃39; 2015-10-16＆＃39; < / p>

请问有什么好的查询语法？实际查询返回空数组。

Answer 1

最后，我找到了解决方案。 您必须使用@JoinTable描述关系表：

@JoinTable(
        name="registration_payment",
        joinColumns = @JoinColumn(name="registration"),
        inverseJoinColumns = @JoinColumn(name = "payment")
)
private List<Payment> payment;

不需要修改@Query：

  

@Query（＆＃34; SELECT p FROM Registration r JOIN r.payment p WHERE r.effect =：effect＆＃34;）

生成的查询是：

  

选择payment2_.uuid为uuid1_9_，payment2_.amount为amount2_9_   来自注册registrati0_   reg join_payment payment1_ on registrati0_.uuid = payment1_.registration   内部加入付款payment2_ on payment1_.payment = payment2_.uuid   registrati0_.effect =？