hibernate 级联删除报更新失败的问题（org.hibernate.exception.GenericJDBCException: Could not execute JDBC batch update）

首先hibernate级联删除的前提是，首先需要在映射文件中配置，配置多表之间的关联关系：

下面以部门表（Dept）和员工表（Emp）为例：

1.在Emp.hbm.xml映射文件中配置many-to-one关系

<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
                                   "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">
<hibernate-mapping>
 <class dynamic-update="true" name="entity.Emp" schema="ACCP" table="EMP">
  <id column="EMPNO" name="empNo" type="java.lang.String" length="20">
   <generator class="assigned"></generator>
  </id>
  <property name="empName" column="EMPNAME" type="java.lang.String" not-null="true"/>
  <many-to-one name="dept" class="entity.Dept">
      <column name="DEPTNO" />
  </many-to-one>
 </class>
</hibernate-mapping>

2.在Dept.hbm.xml映射文件中配置one-to-many关系

<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
                                   "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">
<hibernate-mapping>
 <class dynamic-update="true" name="entity.Dept" schema="ACCP" table="DEPT">
  <id column="DEPTNO" name="deptNo" type="java.lang.String" length="20">
   <generator class="assigned"></generator>
  </id>
  <property name="deptName" column="DEPTNAME" type="java.lang.String" />
  <property name="location" column="LOCATION" type="java.lang.String"  />
  <set name="emps" cascade="all">
      <key column="DEPTNO" />
      <one-to-many class="entity.Emp"/>
  </set>
 </class>
</hibernate-mapping>

3.编写部门和员工的实体类

package entity;

import java.io.Serializable;

public class Emp implements Serializable{
    /**
     * 
     */
    private static final long serialVersionUID = 1L;
    private String empNo;
    private String empName;
    private Dept dept;
    
    public Emp(){}
    
    public Emp(String empNo,String empName){
        this.empNo = empNo;
        this.empName = empName;
    }
    public String getEmpNo() {
        return empNo;
    }
    public void setEmpNo(String empNo) {
        this.empNo = empNo;
    }
    public String getEmpName() {
        return empName;
    }
    public void setEmpName(String empName) {
        this.empName = empName;
    }

    public Dept getDept() {
        return dept;
    }

    public void setDept(Dept dept) {
        this.dept = dept;
    }
    
}

package entity;

import java.io.Serializable;
import java.util.HashSet;
import java.util.Set;

public class Dept implements Serializable{
    /**
     * 
     */
    private static final long serialVersionUID = 1L;
    
    private String deptNo;
    private String deptName;
    private String location;
    
    private Set<Emp> emps = new HashSet<Emp>();
    
    public Dept(){}
    public Dept(String deptNo,String deptName,String location){
        this.deptNo = deptNo;
        this.deptName = deptName;
        this.location = location;
    }
    public String getDeptNo() {
        return deptNo;
    }
    public void setDeptNo(String deptNo) {
        this.deptNo = deptNo;
    }
    public String getDeptName() {
        return deptName;
    }
    public void setDeptName(String deptName) {
        this.deptName = deptName;
    }
    public String getLocation() {
        return location;
    }
    public void setLocation(String location) {
        this.location = location;
    }
    public Set<Emp> getEmps() {
        return emps;
    }
    public void setEmps(Set<Emp> emps) {
        this.emps = emps;
    }
    
    
}

4.测试类

下面只写出测试的方法，

public void deleteDeptAndEmps(){
        currentSession();
        beginTransaction();
        Dept dept = (Dept)session.load(Dept.class, "1001");
        session.delete(dept);
        commitTransaction();
        closeSession();
}

5.进行测试

package test.dao;

import static org.junit.Assert.*;

import org.junit.Ignore;
import org.junit.Test;

import dao.impl.EmpDaoImpl;

public class EmpDaoImplTest extends EmpDaoImpl{
    @Test
    public void testDeleteDeptAndEmps(){
        deleteDeptAndEmps();
    }
}

运行的结果会出现下面错误：

org.hibernate.exception.GenericJDBCException: Could not execute JDBC batch update
    at org.hibernate.exception.SQLStateConverter.handledNonSpecificException(SQLStateConverter.java:126)
    at org.hibernate.exception.SQLStateConverter.convert(SQLStateConverter.java:114)
    at org.hibernate.exception.JDBCExceptionHelper.convert(JDBCExceptionHelper.java:66)
    at org.hibernate.jdbc.AbstractBatcher.executeBatch(AbstractBatcher.java:275)
    at org.hibernate.engine.ActionQueue.executeActions(ActionQueue.java:266)
    at org.hibernate.engine.ActionQueue.executeActions(ActionQueue.java:169)
    at org.hibernate.event.def.AbstractFlushingEventListener.performExecutions(AbstractFlushingEventListener.java:321)
    at org.hibernate.event.def.DefaultFlushEventListener.onFlush(DefaultFlushEventListener.java:50)
    at org.hibernate.impl.SessionImpl.flush(SessionImpl.java:1028)
    at org.hibernate.impl.SessionImpl.managedFlush(SessionImpl.java:366)
    at org.hibernate.transaction.JDBCTransaction.commit(JDBCTransaction.java:137)
    at util.HibernateUtil.commitTransaction(HibernateUtil.java:44)
    at dao.impl.EmpDaoImpl.deleteDeptAndEmps(EmpDaoImpl.java:49)
    at test.dao.EmpDaoImplTest.testDeleteDeptAndEmps(EmpDaoImplTest.java:21)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
    at java.lang.reflect.Method.invoke(Method.java:597)
    at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:44)
    at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:15)
    at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:41)
    at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:20)
    at org.junit.runners.BlockJUnit4ClassRunner.runNotIgnored(BlockJUnit4ClassRunner.java:79)
    at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:71)
    at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:49)
    at org.junit.runners.ParentRunner$3.run(ParentRunner.java:193)
    at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:52)
    at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:191)
    at org.junit.runners.ParentRunner.access$000(ParentRunner.java:42)
    at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:184)
    at org.junit.runners.ParentRunner.run(ParentRunner.java:236)
    at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:50)
    at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:467)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:683)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:390)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:197)
Caused by: java.sql.BatchUpdateException: ORA-01407: 无法更新 ("ACCP"."EMP"."DEPTNO") 为 NULL

    at oracle.jdbc.driver.DatabaseError.throwBatchUpdateException(DatabaseError.java:343)
    at oracle.jdbc.driver.OraclePreparedStatement.executeBatch(OraclePreparedStatement.java:10720)
    at org.hibernate.jdbc.BatchingBatcher.doExecuteBatch(BatchingBatcher.java:70)
    at org.hibernate.jdbc.AbstractBatcher.executeBatch(AbstractBatcher.java:268)
    ... 33 more

重点关注这一条错误：无法更新 ("ACCP"."EMP"."DEPTNO") 为 NULL

这时为什么呢，我们先看看执行hibernate删除时的sql语句：

Hibernate: 
    select
        dept0_.DEPTNO as DEPTNO4_0_,
        dept0_.DEPTNAME as DEPTNAME4_0_,
        dept0_.LOCATION as LOCATION4_0_ 
    from
        ACCP.DEPT dept0_ 
    where
        dept0_.DEPTNO=?
Hibernate: 
    select
        emps0_.DEPTNO as DEPTNO1_,
        emps0_.EMPNO as EMPNO1_,
        emps0_.EMPNO as EMPNO5_0_,
        emps0_.EMPNAME as EMPNAME5_0_,
        emps0_.DEPTNO as DEPTNO5_0_ 
    from
        ACCP.EMP emps0_ 
    where
        emps0_.DEPTNO=?
Hibernate: 
    update
        ACCP.EMP 
    set
        DEPTNO=null 
    where
        DEPTNO=?

从上面我们可以看出，要执行级联删除，要删除Dept表中部门的同时删除Emp表对于部门下的所有员工信息，hibernate是这么干的：

（1）hibernate首先会查询出对应要删除的部门信息

（2）然后级联查询出对于的部门下的所有员工信息

（3）接着更新对于部门下的所有员工，将其部门更新为null

好，问题出现了，报错就在这一个步骤，既然要更新为null，那么Emp表在设计时就要能够让Emp表中的deptNo这个字段能够为null，也就是可以为空，下面就将正确的表

设计显示如下：

好了，上面的勾打上了，那么问题就解决了。

下面我们再执行一次级联删除的方法，看看最终效果：

对于的sql语句情况如下：

Hibernate: 
    select
        dept0_.DEPTNO as DEPTNO4_0_,
        dept0_.DEPTNAME as DEPTNAME4_0_,
        dept0_.LOCATION as LOCATION4_0_ 
    from
        ACCP.DEPT dept0_ 
    where
        dept0_.DEPTNO=?
Hibernate: 
    select
        emps0_.DEPTNO as DEPTNO1_,
        emps0_.EMPNO as EMPNO1_,
        emps0_.EMPNO as EMPNO5_0_,
        emps0_.EMPNAME as EMPNAME5_0_,
        emps0_.DEPTNO as DEPTNO5_0_ 
    from
        ACCP.EMP emps0_ 
    where
        emps0_.DEPTNO=?
Hibernate:  ---------------------------------------------〈〈〈〈看该句下面的变化
    update
        ACCP.EMP 
    set
        DEPTNO=null 
    where
        DEPTNO=?
Hibernate:        
    delete 
    from
        ACCP.EMP 
    where
        EMPNO=?
Hibernate: 
    delete 
    from
        ACCP.DEPT 
    where
        DEPTNO=?

从上面可以得出hibernate执行级联删除的步骤分为5步：

（1）同上

（2）同上

（3）同上

（4）删除Emp表中对应部门的所有信息记录

（5）最后删除Dept表中对应得部门信息

OK，问题解决，通过这个级联删除，使我们能够更加充分的认识hibernate作为持久化工具在处理持久化删除时它的操作方式，是不是很有意思。有问题的话大家可以一起交流。