Hibernate:HQL/QBC查询语言比较的用法 （转载）

如果是首次执行此方法，Hib会从数据库加载关联的order对象，否则就从缓存中得到。

2‘OID检索方式。通过session的get，load方法知道了OID的情况下可以使用

3‘HQL检索方式。使用面向对象的HQL查询语句session的find方法利用HQL来查询

4‘QBC检索方式。利用QBCAPI来检索它是封装了基于字符串的查询语句

5‘本地的SQL检索方式。使用本地数据库的SQL查询语句Hib会负责把检索到的JDBC结果集映射为持久化对象图。

五种检索方式的使用场合和特点：

HQL：是面向对象的查询语言，同SQL有些相似是Hib中最常用的方式。

查询设定各种查询条件。

支持投影查询，检索出对象的部分属性。

支持分页查询，允许使用having和groupby

提供内制的聚集函数，sum()，min()，max()

能调用用户的自定义SQL

支持子查询，嵌入式查询

支持动态绑定参数

建议使用Query接口替换session的find方法。

Query Q = session.createQuery("from customer as c where c.name = :customerName" + "and c.age = :customerAge");
   query.setString ("customerName" , "tom");
   query.setInteger("customerAge" , "21");
   list result = query.list();

Criteria criteria = session.createCriteria(customer.class);
   Criterion criterion1 = Expression.like("name","t%");
   Criterion criterion2 = Expression.eq("age",new Integer(21));
   Critera = criteria.add(criterion1) ;
   Critera = criteria.add(criterion2) ;
   list result = criteria.list();

list result = session.createCriteria(Customer.class).add(Expression.eq("this.name","tom")).list();

Query query  = session.createSQLQuery("select {c.*} from customers c where c.name like : customername " + "and c.age = :customerage","c",customer.calss);
   query.setString("customername","tom");
   query.setInteger("customerage","21");
   list result = query.list();

HQL ：session.createQuery("from employee");
   QBC ：session.createCriteria(employee.class);
   HQL : session.createQuery("from hourlyEmployee");
   QBC : session.createCriteria(hourlyEmployee.class);

fromjava.lang.Object;

fromjava.io.serializable;

////////////查询的排序

1‘查询结果按照客户姓名升序排列：

HQL ：
        Query query = session.createQuery ("from customer c order by c.name");
   QBC ：
        Criteria criteria = session.createCriteria(customer.class);
        criteria.addOrder(order.asc("name"));
   HQL :
        Query query = session.createQuery ("from customer c order by c.name asc , c.age desc");
   QBC :
        Criteria criteria = session.createCriteria(customer.class);
        criteria.addOrder(order.asc ("name"));
        criteria.addOrder(order.desc("age")); 

        import net.sf.hibernate.pression.Order
        import mypack.Order
        ...........
        Criteria criteria = session.createCritria (mypack.Order.class);
        criteria.addOrder(net.sf.hibernate.Order.asc("name"));

setBinary()

setString()

setBoolean()

setByte()

setCalendar()

setCharacter()

setDate()

setDouble()

setText()

setTime()

setTimestamp()

lsit result = session.createQuery ("from order o where o.customer =            :customer").setEntity("customer" , customer).list ;

setProperties()//把命名参数与一个对象的属性值绑定Queryquery=session.createQuery("fromcustomercwherec.name=:name"+"andc.age=:age");

Query.setProperties(customer);

Iterator iterator = session.createQuery("select distinct c.name from customer ").list().iterator();
     while(iterator.hasnext()){
           String name = (String) it.next() ;
     }

integer i = (Integer) session.createQuery("select count(*) from customer").uniqueResult();

integer i = (Integer) session.createQuery("select avg(c.age) from customer c ").uniqueResult();

object [] i = (Integer) session.createQuery("select max(c.age),min(c.age) from customer c ").uniqueResult();
   Integer Maxage = (Integer) i [0];
   Integer Minage = (Integer) i [1];

Integer cout = (Integer) session.createQuery("select count(distinct c.name) from customer c").uniqueResult();

Iterator iterator = (Integer) session.createQuery("select c.name ,count(c) from customer c group by c.name").list.iterator();
   while(iterator.hasnext()){
         object[] p = (objcet[])iterator.next();
         String name = p[0];
         Integer cout = p[1];
   }

Iterator iterator = session.crateQuery("select c.id ,c.name , count(o) from customer c join c.order o group by c.id ").list().iterator;
   while(iterator.hasnext()){
         object[] p = (objcet[])iterator.next();
         Integer id = p[0]
         String name = p[1];
         Integer cout = p[2];
   }

Iterator iterator = session.crateQuery("select c.id ,c.name,sum(o.price) from customer c join c.order o group by c.id").list.iterator();
   while(iterator.hasnext()){
         object[] p = (objcet[])iterator.next();
         Integer id = p[0]
         String name = p[1];
         Double cout = p[2];
   }

tx = session.beginTransaction();
    Iterator customer = session.find("from customer c where c.age > 0").iterator();
    while(iterator.hasnext()){
        customer customer = (customer) customer.next();
        customer.setAge(customer.getAge()+1);
    }
    tx.commit();
    session.close;

tx = session.beginTranscation();
    Connection conn = session.connection();
    Preparedstatement ps = conn.preparedstatment("update customer set age = age + 1 where age > 0 ");
    ps.executeupdate();
    tx.commit();