查询所有用户信息，关联查询订单及订单明细信息及商品信息，订单明细信息中关联查询商品信息

1.1sql主查询表：用户信息关联查询：订单、订单明细，商品信息SELECT   orders.*,  user.username,  user.sex ,  orderdetail.id orderdetail_id,  orderdetail.items_num,  orderdetail.items_id,  items.name items_name,  items.detail items_detailFROM  orders,  USER,  orderdetail,  itemsWHERE orders.user_id = user.id  AND orders.id = orderdetail.orders_id AND items.id = orderdetail.items_id

 

 

 

pojo定义在user.java(主表)中创建映射的属性：集合 List
     
        orderlist在Orders中创建映射的属性：集合List
      
        orderdetails 在Orderdetail中创建商品属性：pojo   Items items
      
     

 

mapper.xml

              SELECT   orders.*,  user.username,  user.sex ,  orderdetail.id orderdetail_id,  orderdetail.items_num,  orderdetail.items_id,  items.name items_name,  items.detail items_detailFROM  orders,  USER,  orderdetail,  itemsWHERE orders.user_id = user.id  AND orders.id = orderdetail.orders_id AND items.id = orderdetail.items_id     

将查询的数据库结果和User接收对象进行映射 
         
             
              
      id是User的属性，user_id是查询的数据库表的列名        
              
              
              
                      
       id是Orders的属性，id是查询的数据库表的列名                
                       
                       
                       
                       
                       
                           
                            
                            
                            
                            
                            
                                
                                 
                                 
                             
                        
               
                      
     

1.1 mapper.java

测试：

// 一对多查询使用resultMap    @Test    public void testFindUserOrderDetail() throws Exception {        SqlSession sqlSession = sqlSessionFactory.openSession();        // 创建mapper代理对象        OrdersMapperCustom ordersMapperCustom = sqlSession                .getMapper(OrdersMapperCustom.class);        // 调用方法        List
     
       list = ordersMapperCustom.findUserOrderDetail();        System.out.println(list);    }