Hibernate的三種查詢方式

Hibernate的三種查詢方式

1.HQL (Hibernate Query Lanuage) 語句，這是類似SQL語句的一種對象化查詢語句.

2.使用Criteria對象，進行按條件查詢(Query by Criteria，簡稱QBC)和按示例查詢(Query by Example 簡稱QBE).

3.生成原生的sql(Native SQL)語句.

Criteria的基本使用

Transaction tx = session.beginTransaction();
Criteria criteria = session.createCriteria(Testbook.class);
List<Testbook> list=criteria.list();
tx.commit();

 

 查詢Testbook 中所有的數據，然後返回

Criteria 接口的核心方法

 

add()      增加一個代表查詢條件的Criterion對象
addOrder()    增加一個代表排序的Criterion對象
createAlias()    創建關聯查詢，爲所關聯的持久化類建立別名
createCriteria()   在相互關聯的持久化類之間建立條件約束
setFirstResult()   設定要獲取的第一條記錄的位置
setMaxResults()    設定要獲取的記錄的最大數量
list()     獲取滿足查詢條件的記錄的集合
uniqueResult()    獲取滿足查詢條件的唯一記錄

 

對查詢結果進行排序

Transaction tx = session.beginTransaction();
Criteria criteria = session.createCriteria(Testbook.class).add(
Restrictions.like("name","任%")).add(Restrictions.between("id",1000,1010));
criteria.addOrder(Order.desc("id")).addOrder(Order.asc("createdTime"));
List<Testbook> list=criteria.list();
tx.commit();

 

實現分頁顯示數據

<span style="font-size: x-small;">Transaction tx = session.beginTransaction();
Criteria criteria = session.createCriteria(Testbook.class).add(
Restrictions.like("name","任%"));
criteria.addOrder(Order.desc("id"));
criteria.setMaxResults(30);
criteria.setFirstResult(10);//setFirstResult()從0開始計數
List<Testbook> list=criteria.list();
tx.commit();</span>

 

 

只查詢一條記錄

Transaction tx = session.beginTransaction();
Criteria criteria = session.createCriteria(Testbook.class).add(
Restrictions.like("name","任%"));
criteria.addOrder(Order.desc("id"));
criteria.setMaxResults(1);
Testbook tb=(Testbook)criteria.uniqueResult();
tx.commit();

 

Restrictions類

<----------------------------------------------------------------------------------------------------------->

 

 

條件"或"方式組合查詢條件

Transaction tx = session.beginTransaction();
Criteria criteria=session.createCriteria(Testbook.class);
Criterion criterion1=Restrictions.or(Restrictions.like("name","任%"),
Restrictions.between("id",1000,1010));
criteria.add(criterion1);
List<Testbook> list=criteria.list();
tx.commit();

 

 

 

使用原生SQL語句設定查詢條件

Transaction tx = session.beginTransaction();
Criteria criteria=session.createCriteria(Testbook.class);
criteria.add(Restrictions.sqlRestriction("{alias}.name=?","Narcissus",Hibernate.STRING));
List<Testbook> list=criteria.list();
tx.commit()

 

 統計函數查詢

Transaction tx = session.beginTransaction();
Criteria criteria=session.createCriteria(Testbook.class);
criteria.setProjection(Projections.max("price"));
Double maxValue=(Double)criteria.uniqueResult();
tx.commit();
System.out.println(maxValue);

 

統計函數組合查詢條件

Transaction tx = session.beginTransaction();
Criteria criteria=session.createCriteria(Testbook.class);
criteria.setProjection(Projections.max("price"));
Double maxValue=(Double)criteria.uniqueResult();
tx.commit();
System.out.println(maxValue);

 

 

獲取多個統計函數的值

Transaction tx = session.beginTransaction();
Criteria criteria=session.createCriteria(Testbook.class);
ProjectionList proList=Projections.projectionList();
proList.add(Projections.max("price"));
proList.add(Projections.min("price"));
proList.add(Projections.avg("price"));
proList.add(Projections.sum("price"));
proList.add(Projections.count("price"));
proList.add(Projections.countDistinct("price"));
proList.add(Projections.rowCount());
criteria.setProjection(proList);
Object values[]=(Object[])criteria.uniqueResult();
tx.commit();

 

 

 

 分組查詢

Transaction tx = session.beginTransaction();
Criteria criteria=session.createCriteria(Testbook.class);
criteria.setProjection(Projections.groupProperty("price"));
List<Double> list=criteria.list();
tx.commit();

 

 分組統計

Transaction tx = session.beginTransaction();
Criteria criteria=session.createCriteria(Testbook.class);
ProjectionList proList=Projections.projectionList();
proList.add(Projections.rowCount());//商品的個數
proList.add(Projections.sum("price"));
proList.add(Projections.groupProperty("name"));
criteria.setProjection(proList);
List<Double> list=criteria.list();
tx.commit();

 

 

 

投影查詢
在一個表中有很多個字段，投影查詢只是查詢某一個或多個字段，也稱局部查詢

 

Transaction tx = session.beginTransaction();
Criteria criteria=session.createCriteria(Testbook.class);
criteria.setProjection(Property.forName("price"));
criteria.add(Restrictions.gt("price",new Double(40.0)))
List<Double> list=criteria.list();
tx.commit();

 

使用Property類的forName()方法實現分組統計

 

Transaction tx = session.beginTransaction();
Criteria criteria=session.createCriteria(Testbook.class);
ProjectionList proList=Projections.projectionList();
proList.add(Projections.forName("price").max());
proList.add(Projections.forName("price").min());
proList.add(Projections.forName("price").avg());
proList.add(Projections.forName("category.id").group().as("c"));
criteria.setProjection(proList);
criteria.addOrder(Order.desc("c"));
List<Object[]> list=criteria.list();
tx.commit();

 

使用DetachedCriteria對象實現離線查詢

//在表現層，構造DetachedCriteria對象，保存用戶動態的查詢條件
DetachedCriteria detchedCriteria=DetachedCriteria.forClass(Testbook.class);
detchedCriteria.add(Restrictions.like("name","任%")).add(Restrictions.between("id",new Integer(1),new Integer(10)));
detchedCriteria.addOrder(Order.desc("id"));

//在業務邏輯層，DetachedCriteria對象與當前的Session對象進行綁定，獲取查詢結果
Session session=HibernateSessionFactoryUtil.getSessionFactory().getCurrentSession();
Transaction tx=detchedCriteria.getExecutableCriteria(session);
List<Testbook> list=criteria.list();
tx.commit();

 

根據示例對象進行查詢

 

 

先定義一個模板然後把這個模板的樣式傳進去，查詢，例如這裏定義的Testbook中的名字爲Narcissus的字段，進行查詢，條件可以爲一個也可以爲多個，對應的就是where中的條件

 

Testbook tb=new Testbook();
tb.setName("Narcissus");
Session session=HibernateSessionFactoryUtil.getSessionFactory().getCurrentSession();
Transaction tx = session.beginTransaction();
Criteria criteria=session.createCriteria(Testbook.class);
Criteria.add(Example.creaate(tb));
List<Testbook> list=criteria.list();
tx.commit();

 

轉載自：http://fehly.iteye.com/blog/642110