多对一的mapper.xml

package com.chentianyu.mapper;
import com.chentianyu.pojo.Orders;
import java.util.List;
public interface OrdersMapper {
    List<Orders> getAllOrders();
}

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper PUBLIC "-//mybatis.org//Mapper 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.chentianyu.mapper.OrdersMapper">
    <!--
    List<Orders> getAllOrders()
    -->
    <resultMap id="ordersmap" type="orders">
        <!--主键id-->
        <id property="id" column="oid"></id>
        <!--非主键id-->
        <result property="orderNumber" column="orderNumber"></result>
        <result property="orderPrice" column="orderPrice"></result>
        <association property="customer" javaType="customer">
            <id property="id" column="cid"></id>
            <result property="name" column="name"></result>
            <result property="age" column="age"></result>
        </association>
    </resultMap>
    <select id="getAllOrders" resultMap="ordersmap">
        select o.id oid,orderNumber,orderPrice,c.id cid,name,age
        from orders o inner join customer c on o.customer_id=c.id;
    </select>
</mapper>

跟一对多一模一样