Hibernate HQL示例十二：DML更新、删除及与Hibernate持久化更新

DML更新及删除

示例：

package com.bjsxt.hibernate;import junit.framework.TestCase;import org.hibernate.Query;import org.hibernate.Session;public class DMLQueryTest extends TestCase {public void testQuery1() {Session session = null;try {session = HibernateUtils.getSession();session.beginTransaction();/** * 使用这种风格的操作，将会造成内存中的对象与数据库中的数据不同步，所以 * 建议尽量少使用:因为hibernate有一级缓存，而更新不更新缓存的数据，只是更新了数据库的数据。 * 应尽量用hibernate的update操作 */Query updateQuery =  session.createQuery("update Student a set a.name=? where a.id in(:ids)");updateQuery.setParameter(0, "张三");updateQuery.setParameterList("ids", new Object[]{1, 2});updateQuery.executeUpdate();session.getTransaction().commit();}catch(Exception e) {e.printStackTrace();session.getTransaction().rollback();}finally {HibernateUtils.closeSession(session);}}public void testQuery2() {Session session = null;try {session = HibernateUtils.getSession();session.beginTransaction();//Query updateQuery =  session.createQuery("delete from Student s where s.id='1'");Query updateQuery =  session.createQuery("delete from Student s where s.id=?").setParameter(0, 2);updateQuery.executeUpdate();session.getTransaction().commit();}catch(Exception e) {e.printStackTrace();session.getTransaction().rollback();}finally {HibernateUtils.closeSession(session);}}}

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我们要更新数据或删除数据，一般会先通过load/get/list查询等使对象进入持久状态，然后直接调用set方法更改属性，hibernate会自动发出一条更新语句进行更新操作。如

public void testQuery3() {Session session = null;try {session = HibernateUtils.getSession();session.beginTransaction();List list = session.createQuery("select s from Student s where s.id=3").list();for (Iterator iterator = list.iterator(); iterator.hasNext();) {Student object = (Student) iterator.next();System.out.println(object.getName());object.setName("yeyeyeye");}session.getTransaction().commit();}catch(Exception e) {e.printStackTrace();session.getTransaction().rollback();}finally {HibernateUtils.closeSession(session);}}

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上例中查询出来的name值的Student对象进入持久状态,马上调用了setName方法执行时的sql:

Hibernate: select student0_.id as id1_, student0_.name as name1_, student0_.createTime as createTime1_, student0_.classid as classid1_ from t_student student0_ where student0_.id=3gooooeeeeoodHibernate: update t_student set name=?, createTime=?, classid=? where id=?

上面：gooooeeeeood为原来的name值，再次查询数据库时name变成了yeyeyeye

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