1 嵌套查询
<select id="findUserWithOrders2" parameterType="Integer"
resultMap="UserWithOrdersResult2">
SELECT * from t_customer where id=#{id}
</select>
<resultMap type="Customer" id="UserWithOrdersResult2">
<id property="id" column="id"/>
<result property="username" column="username"/>
<result property="jobs" column="jobs"/>
<result property="phone" column="phone"/>
<!-- 一对多关联映射：collection
ofType表示属性集合中元素的类型，List<Orders>属性即Orders类 -->
<collection property="ordersList" ofType="Orders" column="id" select="top.lixiang007.mapper.OrdersMapper.findorderByuser"/>
</resultMap>
<select id="findorderByuser" parameterType="Integer" resultType="Orders">
SELECT * from t_order where customer_id=#{id}
</select>
<!-- 一对多：查看某一用户及其关联的订单信息
注意：当关联查询出的列名相同，则需要使用别名区分 -->
<select id="findUserWithOrders" parameterType="Integer"
resultMap="UserWithOrdersResult">
SELECT u.*,o.id as orders_id,o.number
from t_customer u,t_order o
WHERE u.id=o.customer_id
and u.id=#{id}
</select>
<resultMap type="Customer" id="UserWithOrdersResult">
<id property="id" column="id"/>
<result property="username" column="username"/>
<result property="jobs" column="jobs"/>
<result property="phone" column="phone"/>
<!-- 一对多关联映射：collection
ofType表示属性集合中元素的类型，List<Orders>属性即Orders类 -->
<collection property="ordersList" ofType="Orders">
<id property="id" column="id"/>
<result property="number" column="number"/>
</collection>
</resultMap>
