为什么会出现“映射异常”？

Question

我正进入（状态 ：

org.hibernate.MappingException: Foreign key (FKBB979BF4266AA123:address [a_id]))
must have same number of columns as the referenced 
primary key (address [p_id,a_id])

当我尝试运行以下 （尽管不完整） 代码段时：

    public static void main(String args[]) {
        Configuration config = new Configuration().configure();
        SessionFactory sessFact = config.buildSessionFactory();
        Session sess = sessFact.openSession();
        Transaction trans = sess.beginTransaction();    
    }

在hibernate mapping xml如下所示：

<class name="pojo.Person" table="person">
      <id column="p_id" name="personID">
          <generator class="increment" />
      </id>
      <property name="personName" column="p_name" />
      <set name="addressSet" table="address" cascade="all">
          <key column="p_id" />
          <many-to-many class="pojo.Address" column="a_id" />
      </set>
</class>

<class name="pojo.Address" table="address">
      <id column="a_id" name="addressID">
          <generator class="foreign" />
      </id>
      <property name="address" column="address" />
</class>

我正在尝试和班级many to many之间建立联系。Person``Address

发生此异常的原因是什么？

我创建了两个表person并address使用以下sql命令：

CREATE TABLE person(p_id INTEGER,p_name TEXT,PRIMARY KEY(p_id));
CREATE TABLE address(a_id INTEGER,address TEXT);

POJO

人

public class Person {
    private int personID;
    private String personName;
    private Set addressSet;

    public int getPersonID() {
        return personID;
    }

    public void setPersonID(int personID) {
        this.personID = personID;
    }

    public String getPersonName() {
        return personName;
    }

    public void setPersonName(String personName) {
        this.personName = personName;
    }

    public Set getAddressSet() {
        return addressSet;
    }

    public void setAddressSet(Set addressSet) {
        this.addressSet = addressSet;
    }

地址

public class Address {
    private int addressID;
    private String address;
    private Set personSet;

    public int getAddressID() {
        return addressID;
    }

    public void setAddressID(int addressID) {
        this.addressID = addressID;
    }

    public String getAddress() {
        return address;
    }

    public void setAddress(String address) {
        this.address = address;
    }

    public Set getPersonSet() {
        return personSet;
    }

    public void setPersonSet(Set personSet) {
        this.personSet = personSet;
    }

}

Answer 1

对于多对多关系交换，您需要专用的映射表

6.2.4。价值和多对多关联的集合

即，您需要类似PersonAddress表的内容

CREATE TABLE personaddress (p_id integer, a_id integer)

其中p_id是对人员表的FK引用，而a_id是对地址表的FK引用