hibernate---级联保存、级联删除

直接上菜:

dept.hbm.xml:关键点标蓝色这部分,inverse表示放弃维护外键关系,cascade就不用说了

<hibernate-mapping package="com.cissst.it.dept.entity">
<class name="Dept" table="DEPT1">
<id name="deptno" column="DEPTNO">
<generator class="native"></generator>
</id>
<property name="dname" column="DNAME"></property>
<set name="emps" inverse="true" cascade="save-update,delete">
<key column="deptno"></key>
<one-to-many class="com.cissst.it.emp.entity.Emp" />
</set>
</class>
</hibernate-mapping>

emp.hbm.xml

<hibernate-mapping package="com.cissst.it.emp.entity">
<class name="Emp" table="EMP1">
<id name="empno" column="EMPNO">
<generator class="native"></generator>
</id>
<property name="ename" column="ENAME"></property>
<property name="job" column="JOB"></property>
<many-to-one name="dept" class="com.cissst.it.dept.entity.Dept"/>
</class> </hibernate-mapping>

测试类:

    public static void main(String[] args) {
//级联保存
Session session = SessionUtil.openSession();
Transaction tx = session.getTransaction();
tx.begin();
Dept dept = new Dept();
dept.setDname("develop");
Emp emp1 = new Emp();
emp1.setEname("PECOOL");
emp1.setJob("CODE");
Emp emp2 = new Emp();
emp2.setEname("PHOEBE");
emp2.setJob("PHOTO");
HashSet<Emp> set = new HashSet<Emp>();
set.add(emp1);
set.add(emp2);
dept.setEmps(set);
session.save(dept);
tx.commit();
session.close();
}

result:

    只需要保存dept对象,dept中的emp对象也会得到保存,一般1方放弃维护外键关系有助于改善性能,发现sql中明显少了update语句。

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