0

我正在尝试将非主键用作我的应用程序中的外键。这是场景：我有 EMPLOYEE 和 EMPLOYEE_PROPERTIES 表。Employee 和 Employee 属性之间存在一对多的关系。这是我的架构：

create table employee(
 fname varchar2(100) not null,
 lname varchar2(100) not null,
 emp_id number not null
);
ALTER TABLE employee ADD constraint employee_pk PRIMARY KEY (fname, lname);
alter table employee add constraint employee_uniue unique (emp_id);

create table employee_property(
 emp_prop_id not null,
 emp_id number not null,
 property_name varchar2(100) not null,
 property_value varchar2(100) not null
);
ALTER TABLE employee_property ADD constraint employee_property_pk PRIMARY KEY (emp_prop_id);
ALTER TABLE employee_property ADD CONSTRAINT emp_prop_fk FOREIGN KEY (emp_id) REFERENCES employee(emp_id);

这是我的休眠映射 xmls： -----------------Employee------------------------

<hibernate-mapping>
    <class name="com.persistence.vo.Employee" table="EMPLOYEE">
        <composite-id>
            <key-property name="fName" column="FNAME"/>
            <key-property name="lName" column="LNAME"/>
        </composite-id>
        <property name="empId" type="long" access="field" unique="true">
            <column name="EMP_ID" />
        </property>
        <set name="employeeProperties" table="employee_properties" lazy="false"
            fetch="select" cascade="save-update, delete-orphan">
            <key>
                <column name="emp_id" not-null="true"/>
            </key>
            <one-to-many entity-name="com.persistence.vo.EmployeeProperty"/>
        </set>
    </class>
</hibernate-mapping>

--------员工属性------

<hibernate-mapping>
    <class name="com.persistence.vo.EmployeeProperty" table="EMPLOYEE_PROPERTY">
        <id name="empPropId" type="long">
            <column name="EMP_PROP_ID" />
            <generator class="assigned" />
        </id>
    <many-to-one name="employee" class="com.persistence.vo.Employee" fetch="select">
        <column name="empId" not-null="true"/>
    </many-to-one>
        <property name="propertyName" type="java.lang.String">
            <column name="PROPERTY_NAME" />
        </property>
        <property name="propertyValue" type="java.lang.String">
            <column name="PROPERTY_VALUE" />
        </property>
    </class>
</hibernate-mapping>

------------Employee.java--------------

public class Employee {

    private long empId;
    private String fName;
    private String lName;

    private Set<EmployeeProperty> employeeProperties;
}

------------EmployeeProperty.java-------

public class EmployeeProperty {

    private long empPropId;
    private Employee employee;
    private String propertyName;
    private String propertyValue;
}

当我尝试访问员工时，我不断收到以下异常：原因：org.hibernate.MappingException：外键 (FKF28BCC4680C757C:EMPLOYEE_PROPERTY [emp_id])) 必须具有与引用的主键相同的列数 (EMPLOYEE [FNAME,LNAME] )

是否可以引用非主键作为您的外键？

4

1 回答 1

0

我对你的映射感到困惑。Employee 到 EmployeeProperty 是一对多的，但 EmployeeProperty 中的 emp_id 在您的映射中被标记为该实体的 ID 字段（即 PK、Unique 列）？

您有多种选择：

[1] 向 EmployeeProperty 添加另一个字段作为 ID，例如 emp_property_id

[2] 使 EmployeeProperty 成为可嵌入的（没有自己的持久性身份）而不是实体

鉴于 EmployeeProperty 依赖于 Employee（即 EmployeeProperty 不能独立于 Employee 存在），第二个选项可能更正确。

http://en.wikibooks.org/wiki/Java_Persistence/Embeddables

于 2013-11-05T08:59:41.087 回答