Using advanced query techniques - iBATIS in Action - page 133

It maps the order data to the order objects.

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It tells i BATIS what property indicates a new order.

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It tells i BATIS what result map is to be used for any child records.

■

Finally, the order item result map is a normal result map that is only responsible
for mapping the order items to objects. Listing 6.2 shows the mapping for this
example.

Listing 6.2 Using the N+1 Selects solution

<resultMap id="ResultAccountInfoNMap"
class="AccountInfo"
groupBy="account.accountId" >
<result property="account.accountId"
column="accountId" />
<result property="orderList"
resultMap="Ch6.ResultOrderInfoNMap" />
</resultMap>

Declares the result
map for account data

B

<resultMap id="ResultOrderInfoNMap"
class="OrderInfo"
groupBy="order.orderId" >
<result property="order.orderId" column="orderId" />
<result property="orderItemList"
resultMap="Ch6.ResultOrderItemNMap" />
</resultMap>

Declares the result
map for the order data

C

<resultMap id="ResultOrderItemNMap"
class="OrderItem">
<result property="orderId"
column="orderId" />
<result property="orderItemId"
column="orderItemId" />
</resultMap>

Declares the result
map for the order item

D

<select id="getAccountInfoListN"
resultMap="ResultAccountInfoNMap">
select
account.accountId as accountid,
orders.orderid as orderid,
orderitem.orderitemid as orderitemid
from account
join orders on account.accountId = orders.accountId
join orderitem on orders.orderId = orderitem.orderId
order by accountId, orderid, orderitemid
</select>

Ties the result map to
the <select> element

E