Question

我有一个由Hibernate映射的一对多关系中的两个表：

<hibernate-mapping> 
  <class name="Class1" table="TABLE_1" dynamic-update="true">
    <meta attribute="implement-equals">true</meta>   
    <cache usage="read-write"/>

    <id name="id" column="KEY_1" length="5" >

....
    </id>
    <property name="property1a" column="COLUMN_1A" type="string" length="10" />
    <property name="property1b" column="COLUMN_1B" type="string" length="10" />
    <set name="properties2Set" table="TABLE_2" lazy="true" fetch="subselect" cascade="all">
        <key column="FOREIGN_KEY_1"/>
        <composite-element class="Class2">
            <property name="property2a" type="string" column="COLUMN_2A"/>
            <property name="property2b" type="string" column="COLUMN_2B"/>
            <property name="property2c" type="string" column="COLUMN_2C"/>    
    </composite-element>
    </set>
  </class>
</hibernate-mapping>

Class1看起来像：

public class Class1
{
    //... Here the definitions of property1a, property1b

    private Set<Class2> properties2Set = new HashSet<Class2>();


    public Set<Class2> getProperties2Set() 
    {
        return properties2Set;
    }

    public void setProperties2Set(Set<Class2> properties2Set) 
    {
        this.properties2Set = properties2Set;
    }

    // ... Definitions of equals() and hashCode() 
}

Class2包含属性property2a, property2b, property2c。有一个约束

CONSTRAINT PK_OLD PRIMARY KEY (FOREIGN_KEY_1, COLUMN_2A, COLUMN_2B, COLUMN_2C)

我想在表中添加列

COLUMN_ID_NUMBER NUMBER(5) DEFAULT 0 NOT NULL

将约束更改为

CONSTRAINT PK_NEW PRIMARY KEY (FOREIGN_KEY_1, COLUMN_ID_NUMBER)

并生成COLUMN_ID_NUMBER的值，以免违反约束。

在何处添加将映射到COLUMN_ID_NUMBER的属性以及如何生成其值？是否可以保持Class2的结构不变？

Hibernate：在相关表中映射其他列的位置？

0 个答案: