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+++在映射文件中定义命名查询
<class .. >
</class>
<query name="findCustomersByName"><![CDATA[
    from Customer c where c.name like :name
]]></query>
语句:Query q=session.getNamedQuery("findCustomersByName");
     q.setString("name",name);
     List result=query.list();
++++ HQL Vs QBC 检索方式

比较运算
 . 检索年龄大于18的Customer
     HQL  session.createQuery("from Customer cwhere c.age>18");
     QBC  Criteria criteria=session.createCriteria(Customer.class);
          criteria.add(Expression.gt("age",18));
2 . 检索年龄不等于 18的
    HQL session.createQuery("from Customer c where c.age<>18")
    QBC Criteria criteria =session.createCriteria(Customer.class);
        criteria.add(Expression.not(Expression.eq("age",new Integer(18))));
3.  检索姓名为空的Customer对象
   HQL  session.createQuery("from Customer c where c.name is null");
   QBC  Criteria criteria =session.createCriteria(Customer.class);
        criteria.add(Expression.isNull("name"));
4. 检索不属于任何客户的订单
   HQL  session.createQuery("from Order o where o.customer is null");
   QBC  Criteria criteria =session.createCriteria(Order.class);
        criteria.add(Expression.isNull("customer"));
5. HQL  Query q=session.createQuery("from Customer c where lower(c.name)='tom'");
        Query q=session.createQuery("from Customer c where upper(c.name)='TOM'");
   QBC  Criteria criteria =session.createCriteria(Customer.class);
        criteria.add(Expression.eq("name","tom").ignoreCase());
范围运算
1. 检查姓名为 Tom,Mike 或者Jack 的 Customer对象
    HQL session.createQuery("from Customer c where c.name in('Tom','Mike','Jack')");
    QBC Criteria criteria=session.createCriteria(Customer.class);
         String names[]={"Tom","Mike","Jack"};
         criteria.add(Expression.in("name",names));
2. 检查年龄在 18 到  25之间的Customer对象
   HQL session.createQuery("from Customer c where c.age between 18 and 25");
   QBC Criteria criteria=session.createCriteria(Customer.class);
       criteria.add(Expression.between("age",new Integer(18),newInteger(25)))
3. 检索年龄不在 18到  25之间的Customer对象;
   HQL session.createQuery("from Customer c where c.age not between 18 and 25");
   QBC Criteria criteria=session.createCriteria(Customer.class);
       criteria.add(Expression.not(Expression.between("age",new Integer(18),newInteger(25))))
字符串模式匹配
1. 检索姓名以 "T"开头的Customer对象
     HQL  session.createQuery("from Customer cwhere c.name like 'T%'");
     QBC  Criteria criteria=session.createCriteria(Customer.class);
          criteria.add(Expression.like("name","T%"));
           %表示  任意个字符
           _表示  一个字符
          Or
         criteria.add(Expression.like("name","T",MatchMode.START));
      MatchMode 类中有:
                       START    开头
                       END      结尾
                       ANYWHERE 包含
                       EXACT    精确
逻辑运算符
  Expression.and(Expression1,Expression2);
  Expression.or(Expression1,Expression2);
  
连接查询:::::
1 . 映射文件中的配置
lazy="true" 延迟加载
fetch="select" 迫切加载
2.
  2.1  迫切左外连接, HQL : from Customer c left join fetch c.orders o where c.name like 'T'");
                   QBC : criteria.setFetchMode("orders",FetchMode.EAGER); 迫切加载
     QBC 只支持 迫切左外连接,与内连接
  2.2  左外连接,    HQL : from Customer c left join c.orders where c.name like 'T%'
                    
  2.3 内连接     HQl :  from Customer c inner join c.orders o where c.name like 'T%'
          
  
2.4 迫切内连接 ,  HQL:  from customer c inner join fetch c.orders o where c.name like 'T%'
2.5 隐式内连接 , HQL :  from customer c where c.homeAddress.provice like '%hai'
2.6 右外连接  ,   HQL :  from customer right outer join c.orders o where c.name like 'T%'

报表查询 :
   select new mypack.CustomerRow(c.id,c.name,o.orderNumber)
   from customer c join c.orders o
   where o.orderNumber like 'T%'

   distinct 关键字 消除重复关键字
   order by  asc||desc 排序
   group by 列    分组查询
posted on 2011-06-01 21:54 SIMONE 阅读(848) 评论(0)  编辑  收藏 所属分类: JAVA

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