让嵌套结果查询支持PageHelper分页

<resultMap id="myOrdersVO" type="com.imooc.pojo.vo.MyOrdersVO">
  <id column="orderId" property="orderId"/>
  <result column="createdTime" property="createdTime"/>
  <result column="payMethod" property="payMethod"/>
  <result column="realPayAmount" property="realPayAmount"/>
  <result column="postAmount" property="postAmount"/>
  <result column="orderStatus" property="orderStatus"/>
  <result column="isComment" property="isComment"/>

  <collection property="subOrderItemList"
              select="getSubItems"
              column="orderId"
              ofType="com.imooc.pojo.vo.MySubOrderItemVO">
    <result column="itemId" property="itemId"/>
    <result column="itemName" property="itemName"/>
    <result column="itemImg" property="itemImg"/>
    <result column="itemSpecName" property="itemSpecName"/>
    <result column="buyCounts" property="buyCounts"/>
    <result column="price" property="price"/>
  </collection>
</resultMap>

<select id="queryMyOrders" resultMap="myOrdersVO" parameterType="Map">
  SELECT
      od.id as orderId,
      od.created_time as createdTime,
      od.pay_method as payMethod,
      od.real_pay_amount as realPayAmount,
      od.post_amount as postAmount,
      os.order_status as orderStatus,
      od.is_comment as isComment
  FROM
      orders od
  LEFT JOIN
      order_status os
  on od.id = os.order_id
  WHERE
      od.user_id = #{paramsMap.userId}
  AND
      od.is_delete = 0
      <if test="paramsMap.orderStatus != null">
        and os.order_status = #{paramsMap.orderStatus}
      </if>
  ORDER BY
      od.updated_time ASC
</select>
  
<select id="getSubItems" parameterType="String" resultType="com.imooc.pojo.vo.MySubOrderItemVO">
  select
    oi.item_id as itemId,
    oi.item_name as itemName,
    oi.item_img as itemImg,
    oi.item_spec_name as itemSpecName,
    oi.buy_counts as buyCounts,
    oi.price as price
  from
    order_items oi
  where
    oi.order_id = #{orderId}

</select>