HQL中的select子句

一、select子句简介：

二、以对象数组形式返回选择的属性：

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publicvoidtestSelectClauseObjectArray(){

           String hql="select country.ccode,country.cname from Country as country";

           Session session=CustomSessionFactory.getSession();

           Query query=session.createQuery(hql);

           List<Object[]> countries=query.list();

           for(Object[] objects:countries){

                System.out.println("编码："+objects[0]+"   名称："+objects[1]);

           }

           CustomSessionFactory.closeSession();

     }

 

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三、以list形式返回选择的属性：

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publicvoidtestSelectClauseList(){

           String hql="select new list(country.ccode,country.cname) from Country as country";

           Session session=CustomSessionFactory.getSession();

           Query query=session.createQuery(hql);

           List<List> lists=query.list();

           for(List list:lists){

                System.out.println("编码："+list.get(0)+"  名称："+list.get(1));

           }

           CustomSessionFactory.closeSession();

     }

 

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四、以Map的形式返回选择的属性：

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publicvoidtestSelectClauseMap(){

           String hql="select new map(country.ccode as ccode,country.cname as cname) from Country as country";

           Session session=CustomSessionFactory.getSession();

           Query query=session.createQuery(hql);

           List<Map> maps=query.list();

           for(Map map:maps){

                System.out.println("编码："+map.get("ccode")+"     名称："+map.get("cname"));

           }

           CustomSessionFactory.closeSession();

     }

                                  

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五、以自定义类型返回选择的属性：

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publicvoidtestSelectClauseSelf(){

           String hql="select new Country(country.ccode,country.cname) from Country as country";

           Session session=CustomSessionFactory.getSession();

           Query query=session.createQuery(hql);

           List<Country> countries=query.list();

           for(Countrycountry:countries){

                System.out.println("编码："+country.getCcode()+"     名称："+country.getCname());

           }

           CustomSessionFactory.closeSession();

     }

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六、使用distinct关键字去除重复的记录：

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publicvoidtestDistinct(){

           String hql="select distinct country.cname from Country as country";

           Session session=CustomSessionFactory.getSession();

           Query query=session.createQuery(hql);

           List<Object> list=query.list();

           for(Object country:list){

                System.out.println("国家："+country);

           }

           CustomSessionFactory.closeSession();

     }

 

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