关于Hibernate 重复获取主键和关联类的外键的疑问

假定Customer类和Order类之间为双向一对多关联关系.

Customer类包含的属性:

	/**对象OID*/
	private Long id;
	/**Customer对象的姓名*/
	private String name;
	/**Customer对象的年龄*/
	private int age;
	/**与Customer对象的订单*/
	private Set<Order> orders=new HashSet<Order>();

hibernate映射文件:

	<class name="Customer" table="customers">
		<id name="id" type="long" column="id">
			<generator class="native" />
		</id>

		<property name="name" type="string" column="name" />

		<property name="age" type="int" column="age" />

		<set name="orders" cascade="all" inverse="true" lazy="true">
			<key column="customer_id" />
			<one-to-many class="Order" />
		</set>
		
	</class>

Order类包含的属性:

	/**对象OID*/
	private Long id;
	/**Order 对象的订单号*/
	private String orderNumber;
	/**Order 对象的订单价格*/
	private double price;
	/**与Order 对象关联的Customer对象*/
	private Customer customer;

hibernate映射文件:

   <class name="Order" table="orders">
     
      <id name="id" type="long" column="id">
        <generator class="native"/>
      </id>
   
      <property name="orderNumber" type="string"  column="orderNumber" length="15" />
      
      <property name="price"  type="double"  column="price"  />

      <many-to-one name="customer" column="customer_id" class="Customer" />

    </class>

假设数据库中存在的数据为:

cusomters表

orders表:

以下为测试代码:

		List result=session.createQuery("select c from Customer as c inner  join  c.orders  where c.name like 'T%'")
									.list();
		Iterator it = result.iterator();
		Customer customer=(Customer) it.next();
		System.out.println(customer.getOrders().size());

Hibernate生成对应的SQL语句为:

Hibernate: 
    select
        customer0_.id as id4_,
        customer0_.name as name4_,
        customer0_.age as age4_ 
    from
        customers customer0_ 
    inner join
        orders orders1_ 
            on customer0_.id=orders1_.customer_id 
    where
        customer0_.name like 'T%'
Hibernate: 
    select
        orders0_.customer_id as customer4_4_1_,//重复字段
        orders0_.id as id1_,//重复字段
        orders0_.id as id5_0_,
        orders0_.orderNumber as orderNum2_5_0_,
        orders0_.price as price5_0_,
        orders0_.customer_id as customer4_5_0_ 
    from
        orders orders0_ 
    where
        orders0_.customer_id=?

疑问:

上述sql语句中,注释重复字段与下面的字段重复了,为什么要重复检索orders的主键id和外键customer_id字段

另:

上述采用内链接方式检索,但其实做外连接,迫切做外连接,单表查询也会重复检索主键和外键字段