Hibernate的批量查询

 Hibernate的查询大致分为以下三种场景，

　　1.　　HQL查询-hibernate Query Language(多表查询,但不复杂时使用)

 　   2.　　Criteria查询(单表条件查询)

　　3.　　原生SQL查询(复杂的业务查询)

 

接下来解释三种使用方法: 

 1.HQL查询-hibernate Query Language(多表查询,但不复杂时使用)　　Hibernate独家查询语言,属于面向对象的查询语言，HQL语言中不会出现SQL中的表和列，HQL使用的都是JavaBean的类名和属性名。

1.HQL基本查询

(1)查询所有的基本语句

    @Test
    // HQL查询所有数据
    public void fun1() {
        // 1 获得session
        Session session = HibernateUtil.openSession();
        // 2.书写HQL语句
        String hql = "from cn.qlq.domain.Customer";// from 类名全路径
        // 3.根据hql创建查询对象
        Query query = session.createQuery(hql);
        // 4.根据查询对象获取查询结果
        List<Customer> customers = query.list();
        System.out.println(customers);
    }

结果:

Hibernate: 
    select
        customer0_.cust_id as cust_id1_0_,
        customer0_.cust_name as cust_nam2_0_,
        customer0_.cust_source as cust_sou3_0_,
        customer0_.cust_industry as cust_ind4_0_,
        customer0_.cust_level as cust_lev5_0_,
        customer0_.cust_linkman as cust_lin6_0_,
        customer0_.cust_phone as cust_pho7_0_,
        customer0_.cust_mobile as cust_mob8_0_ 
    from
        cst_customer customer0_
[Customer [cust_id=1, cust_name=XXXXXXXXXX], Customer [cust_id=2, cust_name=联想]]

改进:如果整个项目中只有一个类的名字可以省略包路径，也就是可以只写类名:

    @Test
    // HQL查询所有数据
    public void fun1() {
        // 1 获得session
        Session session = HibernateUtil.openSession();
        // 2.书写HQL语句
//        String hql = "from cn.qlq.domain.Customer";// from 类名全路径
        String hql = "from Customer";// 如果整个项目中只有这一个类名可以直接写名字
        // 3.根据hql创建查询对象
        Query query = session.createQuery(hql);
        // 4.根据查询对象获取查询结果
        List<Customer> customers = query.list();
        System.out.println(customers);
    }

(2)根据主键查询单个

    @Test
    // HQL查询单个数据
    public void fun2() {
        // 1 获得session
        Session session = HibernateUtil.openSession();
        // 2.书写HQL语句
//        String hql = "from cn.qlq.domain.Customer";// from 类名全路径
        String hql = "from Customer where cust_id = 1";// where后面是Customer的属性名称而不是列名
        // 3.根据hql创建查询对象
        Query query = session.createQuery(hql);
        // 4.根据查询对象获取查询结果
        Customer customer = (Customer) query.uniqueResult();
        System.out.println(customer);
    }

 2.HQL条件查询:

 (1)?占位符查询

　　类似于JDBC的占位符，只是hibernate的?下标从0开始，而JDBC的下标从1开始，基本上所有的编程索引都从0开始，唯独JDBC从1开始。。。。

    @Test
    // HQL的?占位符查询
    public void fun3() {
        // 1 获得session
        Session session = HibernateUtil.openSession();
        // 2.书写HQL语句
//        String hql = "from cn.qlq.domain.Customer";// from 类名全路径
        String hql = "from Customer where cust_id = ?";// 如果整个项目中只有这一个类名可以直接写名字
        // 3.根据hql创建查询对象
        Query query = session.createQuery(hql);
//        query.setLong(0, 1l);//类似于JDBC的占位符，只是JDBC的占位符下标从0开始，hibernate从1开始
        query.setParameter(0, 1l);//这种写法不用管类型
        // 4.根据查询对象获取查询结果
        Customer customer = (Customer) query.uniqueResult();
        System.out.println(customer);
    }

 (2)命令占位符   ：name格式的查询，固定格式，name随便起，习惯性的起做和条件名字一样

    @Test
    // HQL的命令占位符查询
    public void fun4() {
        // 1 获得session
        Session session = HibernateUtil.openSession();
        // 2.书写HQL语句
//        String hql = "from cn.qlq.domain.Customer";// from 类名全路径
        String hql = "from Customer where cust_id = :cust_id";// :cust_id的名字随便起，只不过习惯性的起做一样
        // 3.根据hql创建查询对象
        Query query = session.createQuery(hql);
//        query.setLong(0, 1l);//类似于JDBC的占位符，只是JDBC的占位符下标从0开始，hibernate从1开始
        query.setParameter("cust_id",1l);
        // 4.根据查询对象获取查询结果
        Customer customer = (Customer) query.uniqueResult();
        System.out.println(customer);
    }

3.HQL排序与分页查询

 　　分页查询类似于mysql的limit关键字，limit start，pageSize。。。。。。

    @Test
    // HQL分页查询
    public void fun5() {
        // 1 获得session
        Session session = HibernateUtils.openSession();
        // 2.书写HQL语句
//        String hql = "from cn.qlq.domain.Customer";// from 类名全路径
        String hql = "from Customer order by cust_id desc";// :cust_id的名字随便起，只不过习惯性的起做一样
        // 3.根据hql创建查询对象
        Query query = session.createQuery(hql);
        /**
         * 类似于 limit start,pageSize;
         * 假设页大小是2
         * 页号 起始值  页大小
         * 1   0    2
         * 2   2    2
         */
        //例如取第二页数据
        query.setFirstResult(2);
        query.setMaxResults(2);
        // 4.根据查询对象获取查询结果
         List<Customer> customers = query.list();
        System.out.println(customers);
    }

结果:

Hibernate: 
    select
        customer0_.cust_id as cust_id1_0_,
        customer0_.cust_name as cust_nam2_0_,
        customer0_.cust_source as cust_sou3_0_,
        customer0_.cust_industry as cust_ind4_0_,
        customer0_.cust_level as cust_lev5_0_,
        customer0_.cust_linkman as cust_lin6_0_,
        customer0_.cust_phone as cust_pho7_0_,
        customer0_.cust_mobile as cust_mob8_0_ 
    from
        cst_customer customer0_ limit ?,
        ?

[Customer [cust_id=2, cust_name=新增数据], Customer [cust_id=1, cust_name=程序员111]]

2.Criteria查询(单表条件查询)

　　criteria查询相比于上面的HQL查询要简单的多。

 1.基本查询---查询所有

    @Test
    // 查询所有
    public void test1() {
        // 1 获得session
        Session session = HibernateUtils.openSession();
        // 2.創建criteria进行查询
        Criteria criteria = session.createCriteria(Customer.class);
        List<Customer> list = criteria.list();
        System.out.println(list);
    }

结果:

[Customer [cust_id=1, cust_name=程序员111], Customer [cust_id=2, cust_name=新增数据], Customer [cust_id=3, cust_name=测试名称222], Customer [cust_id=4, cust_name=测试名称222]]

2. 条件查询单个:

    @Test
    // 根据ID查询单个,条件查询
    public void test2() {
        // 1 获得session
        Session session = HibernateUtils.openSession();
        // 2.創建criteria进行查询
        Criteria criteria = session.createCriteria(Customer.class);
        criteria.add(Restrictions.eq("cust_id", 1l));
        Customer customer = (Customer) criteria.uniqueResult();
        System.out.println(customer);
    }

结果:

Customer [cust_id=1, cust_name=程序员111]

条件列表:

 3.分页查询:

    @Test
    // 分页查询
    public void test3() {
        // 1 获得session
        Session session = HibernateUtils.openSession();
        // 2.創建criteria进行查询
        Criteria criteria = session.createCriteria(Customer.class);
        /**
         * 类似于 limit start,pageSize;
         * 假设页大小是2
         * 页号 起始值  页大小
         * 1   0    2
         * 2   2    2
         */
        criteria.setFirstResult(2);
        criteria.setMaxResults(2);
        List<Customer> list = criteria.list();
        System.out.println(list);
    }

结果:

[Customer [cust_id=3, cust_name=测试名称222], Customer [cust_id=4, cust_name=测试名称222]]

4.排序分组使用

    @Test
    // 排序和分组
    public void test5() {
        // 1 获得session
        Session session = HibernateUtils.openSession();
        // 2.排序
        Criteria criteria = session.createCriteria(Customer.class);
        criteria.addOrder(Order.desc("cust_id"));
        List<Customer> list = criteria.list();
        System.out.println(list);
        System.out.println();
        // 2.分组
        Criteria criteria1 = session.createCriteria(Customer.class);
        criteria1.setProjection(Projections.groupProperty("cust_name"));
        List<Customer> list1 = criteria1.list();
        System.out.println(list1);
    }

 结果：

[Customer [cust_id=4, cust_name=测试名称222], Customer [cust_id=3, cust_name=测试名称222], Customer [cust_id=2, cust_name=新增数据], Customer [cust_id=1, cust_name=程序员111]]

[新增数据, 测试名称222, 程序员111]

5.聚集函数查询总数

    @Test
    // 查询总数（聚集函数的使用）
    public void test4() {
        // 1 获得session
        Session session = HibernateUtils.openSession();
        // 2.聚集函数查询总数
        Criteria criteria = session.createCriteria(Customer.class);
        criteria.setProjection(Projections.rowCount());
        Long count = (Long) criteria.uniqueResult();
        System.out.println(count);
        // 3.聚集函数查询总数第二种方法
        Criteria criteria1 = session.createCriteria(Customer.class);
        criteria1.setProjection(Projections.count("cust_id"));
        Long count1 = (Long) criteria.uniqueResult();
        System.out.println(count1);
        // 4.聚集函数查询几个不同的姓名
        Criteria criteria2 = session.createCriteria(Customer.class);
        criteria2.setProjection(Projections.countDistinct("cust_name"));
        Long count2 = (Long) criteria2.uniqueResult();
        System.out.println(count2);
    }

 结果:

4
4
3

3.Hibernate种的原生SQL查询(用于处理一些复杂的业务逻辑)

1.基本查询

1.查询结构是数组集合

    @Test
    // 基本查询--返回数组list
    public void test1() {
        // 1.获取与线程绑定的session
        Session session = HibernateUtils.getCurrentSession();
        // 2.开启事务
        Transaction tx = session.beginTransaction();
        String sql = "select * from cst_customer";// 3.构造Query对象进行查询
        SQLQuery sqlQuery = session.createSQLQuery(sql);
        List<Object[]> list = sqlQuery.list();
        for (Object[] o : list) {
            System.out.println(Arrays.toString(o));
        }
        // 提交事务
        tx.commit();
    }

结果

[1, 程序员111, null, null, null, null, null, null]
[2, 新增数据, null, null, null, null, null, null]
[3, 测试名称222, null, null, null, null, null, null]
[4, 测试名称222, null, null, null, null, null, null]

2.查询结果是对象集合(重要)

    @Test
    // 基本查询--返回对象list
    public void test2() {
        // 1.获取与线程绑定的session
        Session session = HibernateUtils.getCurrentSession();
        // 2.开启事务
        Transaction tx = session.beginTransaction();
        String sql = "select * from cst_customer";// 3.构造Query对象进行查询
        SQLQuery sqlQuery = session.createSQLQuery(sql);
        sqlQuery.addEntity(Customer.class);
        List<Customer> list = sqlQuery.list();
        System.out.println(list);
        // 提交事务
        tx.commit();
    }

结果

[Customer [cust_id=1, cust_name=程序员111], Customer [cust_id=2, cust_name=新增数据], Customer [cust_id=3, cust_name=测试名称222], Customer [cust_id=4, cust_name=测试名称222]]

2.条件查询

    @Test
    // 基本查询--返回对象list
    public void test3() {
        // 1.获取与线程绑定的session
        Session session = HibernateUtils.getCurrentSession();
        // 2.开启事务
        Transaction tx = session.beginTransaction();
        String sql = "select * from cst_customer where cust_id=?";// 3.构造Query对象进行查询
        SQLQuery sqlQuery = session.createSQLQuery(sql);
        sqlQuery.addEntity(Customer.class);
        sqlQuery.setParameter(0, 1l);
        Customer cus = (Customer) sqlQuery.uniqueResult();
        System.out.println(cus);
        // 提交事务
        tx.commit();
    }

结果

Customer [cust_id=1, cust_name=程序员111]

3.聚集函数查询总数

    @Test
    // 基本查询--查询总数
    public void test4() {
        // 1.获取与线程绑定的session
        Session session = HibernateUtils.getCurrentSession();
        // 2.开启事务
        Transaction tx = session.beginTransaction();
        String sql = "select count(*) from cst_customer";// 3.构造Query对象进行查询
        SQLQuery sqlQuery = session.createSQLQuery(sql);
        BigInteger bg = (BigInteger) sqlQuery.uniqueResult();
        System.out.println(bg);
        // 提交事务
        tx.commit();
    }

结果

4

4.排序与分页综合查询

    @Test
    // 基本查询--分页查询
    public void test5() {
        // 1.获取与线程绑定的session
        Session session = HibernateUtils.getCurrentSession();
        // 2.开启事务
        Transaction tx = session.beginTransaction();
        //按cust_id降序排序
        String sql = "select *  from cst_customer order by cust_id desc limit ?,?";// 3.构造Query对象进行查询
        SQLQuery sqlQuery = session.createSQLQuery(sql);
        sqlQuery.addEntity(Customer.class);
        /**
         * 分页查询  取第二页，页大小是二
         */
        sqlQuery.setParameter(0, 2);
        sqlQuery.setParameter(1, 2);
        List<Customer> list = sqlQuery.list();
        System.out.println(list);
        // 提交事务
        tx.commit();
    }

结果

[Customer [cust_id=2, cust_name=新增数据], Customer [cust_id=1, cust_name=程序员111]]

4.原生SQL映射为MAP:

@Test
    /**
     * 原生SQL查询(SQLQuery映射查询结果为map)
     */
    public void fun6(){
        Session session = HibernateUtil.openSession();
        Transaction tx = session.beginTransaction();
        
        String sql = "select * from cst_customer";
        SQLQuery sqlQuery = session.createSQLQuery(sql);
        sqlQuery.setResultTransformer(Transformers.ALIAS_TO_ENTITY_MAP);
        System.out.println(sqlQuery.list());
        
        tx.commit();
        session.close();
    }

结果:

[{cust_phone=null, cust_name=测试名称1, cust_mobile=null, cust_linkman=null, cust_industry=null, cust_level=null, cust_source=null, cust_id=7}, {cust_phone=null, cust_name=测试名称2, cust_mobile=null, cust_linkman=null, cust_industry=null, cust_level=null, cust_source=null, cust_id=8}, {cust_phone=null, cust_name=测试名称3, cust_mobile=null, cust_linkman=null, cust_industry=null, cust_level=null, cust_source=null, cust_id=9}, {cust_phone=null, cust_name=测试名称4, cust_mobile=null, cust_linkman=null, cust_industry=null, cust_level=null, cust_source=null, cust_id=10}, {cust_phone=null, cust_name=测试名称5, cust_mobile=null, cust_linkman=null, cust_industry=null, cust_level=null, cust_source=null, cust_id=11}, {cust_phone=null, cust_name=测试名称6, cust_mobile=null, cust_linkman=null, cust_industry=null, cust_level=null, cust_source=null, cust_id=12}, {cust_phone=null, cust_name=测试名称7, cust_mobile=null, cust_linkman=null, cust_industry=null, cust_level=null, cust_source=null, cust_id=13}]

 

5.hibernate原生SQL进行插入操作

    @Test
    // 原生SQL执行插入操作
    public void test6() {
        // 1.获取与线程绑定的session
        Session session = HibernateUtils.getCurrentSession();
        // 2.开启事务
        Transaction tx = session.beginTransaction();
        String sql = "insert into user values('xxxx','李四',23)";;// 3.构造Query对象进行插入
        SQLQuery sqlQuery = session.createSQLQuery(sql);
        sqlQuery.executeUpdate();
        // 提交事务
        tx.commit();
    }