外置命名查询 查询过滤器 分页查询 对象导航查询 连接查询 统计查询 DML风格的操作

5、外置命名查询

       * 在映射文件中采用<query>标签来定义hql

       * 在程序中采用session.getNamedQuery()方法得到hql查询串

       参见：Student.hbm.xml、NameQueryTest.java

      

6、查询过滤器    

       * 在映射文件中定义过滤器参数

       * 在类的映射中使用这些参数

       * 在程序中启用过滤器

       参见：Student.hbm.xml、FilterQueryTest.java

      

7、分页查询【重要】 

       * setFirstResult()，从0开始

       * setMaxResults,每页显示多少条数据

       参见：PageQueryTest.java

                      

8、对象导航查询，在hql中采用 . 进行导航【重要】

       参见：ObjectNavQueryTest.java

      

9、连接查询【重要】

       * 内连

       * 外连接（左连接/右连接）     

       参见：JoinQueryTest.java

      

10、统计查询【重要】

       参见：StatQueryTest.java

      

11、DML风格的操作（尽量少用，因为和缓存不同步）

       参见：DMLQueryTest.java

/**

 * 外置命名查询

 * @author Administrator

 *

 */

<query name="searchStudents">

       <![CDATA[

           SELECT s FROM Student s where s.id<?

       ]]>

    </query>放在任何一个映射文件

    List students = session.getNamedQuery("searchStudents")

                            .setParameter(0, 10)

                            .list();

           for (Iterator iter=students.iterator(); iter.hasNext();) {

              Student student = (Student)iter.next();

              System.out.println(student.getName());

           }

 

 

/**

 * 查询过滤器

 * @author Administrator

 *

 */

    <class name="com.bjsxt.hibernate.Student" table="t_student">

       <id name="id">

           <generator class="native"/>

       </id>

       <property name="name"/>

       <property name="createTime"/>

       <many-to-one name="classes" column="classesid"/>

       <filter name="filtertest" condition="id &lt; :myid"/>

    </class>

 

    <filter-def name="filtertest">

       <filter-param name="myid" type="integer"/>

    </filter-def>

   

 

 

           session.enableFilter("filtertest")

                  .setParameter("myid", 10);  

          

           List students = session.createQuery("from Student").list();

           for (Iterator iter=students.iterator(); iter.hasNext();) {

              Student student = (Student)iter.next();

              System.out.println(student.getName());

           }

 

 

/**

 * 分页查询

 * @author Administrator

 *

 */

    List students = session.createQuery("from Student")

                                .setFirstResult(1)//从哪里开始

                                .setMaxResults(2)//每页显示多少条数据

                                .list();

           for (Iterator iter=students.iterator(); iter.hasNext();) {

              Student student = (Student)iter.next();

              System.out.println(student.getName());

           }

 

 

 

 

/**

 * 对象导航查询

 * @author Administrator

 *

 */

           List students = session.createQuery("select s.name from Student s where s.classes.name like '%1%'").list();

 

 

/**

 * 连接查询

 * @author Administrator

 *

 */

 

      

           //List students = session.createQuery("select c.name, s.name from Student s join s.classes c").list();

           List students = session.createQuery("select c.name, s.name from Student s inner join s.classes c").list();

           List students = session.createQuery("select c.name, s.name from Classes c left join c.students s").list();

 

 

/**

 * 统计查询

 * @author Administrator

 *

 */

      

//         List students =session.createQuery("select count(*) from Student").list();

//         Long count = (Long)students.get(0);

//         System.out.println(count);

 

           Long count = (Long)session.createQuery("select count(*) from Student").uniqueResult();

           System.out.println(count);

          

 

    List students =session.createQuery("select c.name, count(s) from Student s join s.classes c " +

                  "group by c.name order by c.name").list();

      

 

/**

 * DML风格的操作

 * @author Administrator

 *

 */

   

    session.createQuery("update Student s set s.name=? where s.id < ?")

                  .setParameter(0, "李四")

                  .setParameter(1, 5)

                  .executeUpdate();