JPA： - 许多一对多只有一个关联表的外键

Question

我与这些注释的多对多的关联映射两类：

@Entity 
@Inheritance(strategy=InheritanceType.TABLE_PER_CLASS) 
public abstract class TechnicalItem extends GenericBusinessObject implements Resumable{ 

    @SequenceGenerator(name="TECHNICAL_ITEM_ID_GEN", sequenceName="TECHNICAL_ITEM_ID_SEQ") 
    @Id 
    @Column(name = "\"ID\"", nullable = false) 
    @GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "TECHNICAL_ITEM_ID_GEN") 
    private int id; 


    @ManyToMany(mappedBy = "referencePerformanceItems", fetch=FetchType.LAZY) 
    private List<TestingRate> testingRates; 
} 

@Entity 
@DiscriminatorValue("T") 
public class TestingRate extends Rate { 


    @ManyToMany(fetch=FetchType.LAZY) 
    @JoinTable(name="ecc.\"TESTING_RATE_TECHNICAL_ITEM\"", 
     joinColumns = {@JoinColumn(name = "\"TESTING_RATE_ID\"")}, 
     inverseJoinColumns = {@JoinColumn(name = "\"TECHNICAL_ITEM_ID\"")}) 
    //@ManyToMany(mappedBy = "testingRates", fetch=FetchType.LAZY) 
    private List<TechnicalItem> referencePerformanceItems; 
} 

用SQL的关联表的创建产生的是：

create table ecc."TESTING_RATE_TECHNICAL_ITEM" (
    "TESTING_RATE_ID" int4 not null, 
    "TECHNICAL_ITEM_ID" int4 not null 
); 
alter table ecc."TESTING_RATE_TECHNICAL_ITEM" 
    add constraint FKC5D64DF6A2FE2698 
    foreign key ("TESTING_RATE_ID") 
    references ecc."RATE"; 

没有提到第二个外键“TECHNICAL_ITEM_ID”（应该在关联表中的复合外键的第二部分）。 这是正常行为吗？ 如果我想要我的2列是2个外键引用我关心的2个表的主键，我应该怎么做映射。

我使用PostGreSQL数据库和Hibernate作为JPA提供程序。

Answer 1

确保您没有错过第二个约束。我有类似的情况，Hibernate生成数据库架构很好

@ManyToMany(targetEntity = Two.class, cascade = { 
    CascadeType.ALL 
}) 
@JoinTable(name = "ONE_M2MJT_TWO", joinColumns = { 
    @JoinColumn(name = "ONE_ID") 
}, inverseJoinColumns = { 
    @JoinColumn(name = "TWO_ID") 
}, uniqueConstraints = { 
    @UniqueConstraint(columnNames = { 
     "ONE_ID", 
     "TWO_ID" 
    }) 
}) 
public List<Two> getManyToManyJoinTable() { ... } 


create table ONE (MY_SUPER_ID bigint generated by default as identity (start with 1), VALUE_ varchar(255), primary key (MY_SUPER_ID)) 
create table ONE_M2MJT_TWO (ONE_ID bigint not null, TWO_ID bigint not null, unique (ONE_ID, TWO_ID)) 
create table TWO (MY_SUPER_ID bigint generated by default as identity (start with 1), VALUE_ varchar(255), primary key (MY_SUPER_ID)) 
alter table ONE_M2MJT_TWO add constraint FKA575066C950B44B foreign key (TWO_ID) references TWO 
alter table ONE_M2MJT_TWO add constraint FKA575066C045060B foreign key (ONE_ID) references ONE