Hibernate5.2之原生SQL查询

                                                                                                                                       Hibernate5.2之原生SQL查询

一. 介绍

　　 在上一篇博客中笔者通过代码的形式给各位读者介绍了Hibernate中最重要的检索方式--HQL查询。在本博文中笔者将向各位读者介绍Hibernate中的原生SQL查询，虽为原生SQL查询，但是笔者认为Hibernate在针对不同的数据库在分页语句的处理上做的很不错，我们不用去关心使用的是何种的数据库。本博文会沿用《Hibernate5.2之HQL查询》中的POJO类和配置文件，请各位看官在阅读本博文之前请先阅读该文章，本篇文章会将HQL中涉及的相关操作原封不动的全部改为SQL查询，所以在代码上的重复度比较的高，请各位读者勿喷，那我们就直接上单元测试了。

二. 单元测试

A.获取所有的Order对象，得到一个List集合

@Test
public void list(){
    String sql = "select * from orders";
    NativeQuery<Order> query = session.createNativeQuery(sql, Order.class);
    List<Order> list = query.getResultList();
    for(Order o : list){
         System.out.println(o.getId() + "::" + o.getOrderId());
    }
}

B.获取Order的分页数据，得到一个List集合

/**
 * 虽然为原生的SQL查询，但是依然可以使用setFirstResult()和setMaxResults()方法。从而屏蔽了
 * 底层数据库的差异性。
 */
@Test
public void pageList(){
    String sql = "select * from orders";
    //setFirstResult()从0开始
    Query<Order> query = session.createNativeQuery(sql, Order.class).setFirstResult(1).setMaxResults(4);
    List<Order> list = query.getResultList();
    for(Order o : list){
         System.out.println(o.getId());
    }
}

C.多条件查询，返回List集合(第一种形式：索引占位符)

@Test
public void multiCretiera(){
    String sql = "select * from orders where create_time between ? and ? and order_id like ?";
    Query<Order> query = session.createNativeQuery(sql, Order.class);
    String beginDateStr = "2016-07-26 00:00:00";
    String endDateStr = "2016-07-28 23:59:59";
    SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd hh:mm:ss");
    Date beginDate = null;
    Date endDate = null;
    try {
         beginDate = sdf.parse(beginDateStr);
         endDate = sdf.parse(endDateStr);
    } catch (ParseException e) {
         e.printStackTrace();
    }
    //分页从0开始
    query.setParameter(0, beginDate).setParameter(1, endDate).setParameter(2, "%D%").setFirstResult(0).setMaxResults(1);
    List<Order> list = query.getResultList();
    for(Order o : list){
         System.out.println(o.getOrderId() + "::" + o.getCreateTime());
    }
}

D.多条件查询，返回List集合(第二种形式：命名占位符)

@Test
public void multiCretiera1(){
    String sql = "select * from orders where order_id like :orderId and create_time between :beginDate and :endDate";
    Query<Order> query = session.createNativeQuery(sql, Order.class);
    String beginDateStr = "2016-07-26 00:00:00";
    String endDateStr = "2016-07-28 23:59:59";
    SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd hh:mm:ss");
    Date beginDate = null;
    Date endDate = null;
    try {
         beginDate = sdf.parse(beginDateStr);
         endDate = sdf.parse(endDateStr);
    } catch (ParseException e) {
         e.printStackTrace();
    }
    query.setParameter("orderId", "%D%").setParameter("beginDate", beginDate).setParameter("endDate", endDate);
    List<Order> list = query.getResultList();
    for(Order o : list){
         System.out.println(o.getId() + "::" + o.getOrderId());
    }
}

E.大于条件的查询，使用索引占位符

@Test
public void gt(){
    String sql = "select * from orders where id > ?";
    Query<Order> query = session.createNativeQuery(sql, Order.class).setParameter(0, 3);
    List<Order> list = query.getResultList();
    for(Order o : list){
        System.out.println(o.getId() + "::" + o.getOrderId());
    }
}

F.删除操作

@Test
public void delete(){
    String sql = "delete from orders where id in (:idList)"; 
    Transaction tx = session.beginTransaction();
    List<Integer> list = new ArrayList<Integer>();
    list.add(1);
    list.add(2);
    Query<?> query = session.createNativeQuery(sql).setParameter("idList", list);
    int i = query.executeUpdate();
    System.out.println(i);
    tx.commit();
    session.close();
}

G.获取某一列的值

@Test
public void singleValue(){
    String sql = "select order_id from orders";
    Query<String> query = session.createNativeQuery(sql);
    List<String> list = query.getResultList();
    for(String str : list){
        System.out.println(str);
    }
}

 H.获取关联对象的结果集

@Test
public void getCustomer(){
    String sql = "select c.* from orders o join customer c on o.customer_id = c.id where c.id = 8";
    Query<Customer> query = session.createNativeQuery(sql, Customer.class);
    List<Customer> list = query.getResultList();
    for(Customer o : list){
        System.out.println(o.getId() + ";;");
    }
}

 I.多列数据的查询

@Test
public void getObjectArray(){
    String sql = "select c.name, c.phone_number, o.order_id, o.create_time from orders o join customer c on o.customer_id = c.id";
    Query<Object[]> query = session.createNativeQuery(sql);
    List<Object[]> list = query.getResultList();
    for(Object[] o : list){
         System.out.println(o[0] + ";;" + o[1] + ";;" + o[2]);
    }
}

J.函数查询

@Test
public void functionQuery(){
    String sql = "select max(id), count(*) from orders";
    Query<Object[]> query = session.createNativeQuery(sql);
    Object[] obj = query.getSingleResult();
    System.out.println(obj[0] + "::" + obj[1]);
}

 K.排序

@Test
public void descQuery(){
    String sql = "select * from orders order by id desc";
    Query<Order> query = session.createNativeQuery(sql, Order.class);
    List<Order> list = query.getResultList();
    for(Order o : list){
        System.out.println(o.getId() + "::" + o.getOrderId());
    }
}

L.右连接

@Test
public void rightJoin(){
    String sql = "select c.* from orders o right join customer c on o.customer_id = c.id";
    Query<Customer> query = session.createNativeQuery(sql, Customer.class);
    List<Customer> list = query.getResultList();
    for(Customer c : list){
        System.out.println(c.getId());
    }
}

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