Hibernate 是如何管理数据库表的关联关系的

Hibernate 是如何管理数据库表的关联关系的

数据库的关联关系是通过主外键实现的： 

Hibernate中管理的实体类的关联关系是通过包含来实现的，根据关联的2方是否相互包含分为单向关联和双向关联：

Hibernate 配置实体关联不仅仅要在实体类中包含关联类，而且要在hbm映射文件中说明。 

 

 

一对一外键关联 

Class Team()

{

Int teamid;

String teamname;

Address address;

 

}

 

<hibernate-mapping>
    <class name="com.suxiaolei.hibernate.pojos.Team" table="team">
        <id name="id" type="integer">
            <column name="id"></column>
            <generator class="increment"></generator>
        </id>

        <property name="name" column="name" type="string"></property>
        
        <many-to-one name="adress" class="com.suxiaolei.hibernate.pojos.Adress" column="adress_id" unique="true"></many-to-one>

    </class>
</hibernate-mapping>

 

Class Address()

{

Int addId;

String city;

String detailAdd;

 

Team team;

} 

 

<hibernate-mapping>
    <class name="com.suxiaolei.hibernate.pojos.Adress" table="adress">
        <id name="id" type="integer">
            <column name="id"></column>
            <generator class="increment"></generator>
        </id>

        <property name="city" column="city" type="string"></property>
        
        <one-to-one name="team" class="com.suxiaolei.hibernate.pojos.Team" cascade="all"></one-to-one>

    </class>

  

一对一主键关联

Class Team()

{

Int teamid;

String teamname;

Address address;

 

}

 

 

 

<hibernate-mapping>
    <class name="com.suxiaolei.hibernate.pojos.Team" table="team">
        <id name="id" type="integer">
            <column name="id"></column>
            <generator class="foreign">
                <param name="property">adress</param>
            </generator>
        </id>

        <property name="name" column="name" type="string"></property>
        
        <one-to-one name="adress" class="com.suxiaolei.hibernate.pojos.Adress" cascade="all"></one-to-one>

    </class>
</hibernate-mapping>

 

 

 

Class Address()

{

Int addId;

String city;

String detailAdd;

 

Team team;

}

<class name="com.suxiaolei.hibernate.pojos.Adress" table="adress">
        <id name="id" type="integer">
            <column name="id"></column>
            <generator class="increment"></generator>
        </id>

        <property name="city" column="city" type="string"></property>
        
        <one-to-one name="team" class="com.suxiaolei.hibernate.pojos.Team" cascade="all"></one-to-one>

    </class>

 

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