Mybatis中resultMap使用注意

    <resultMap id="omsOrderReturnApplyResult" type="com.mymall.dto.OmsOrderReturnApplyResult"
               extends="com.mymall.mapper.OmsOrderReturnApplyMapper.BaseResultMap">
        <association property="companyAddress" resultMap="com.mymall.mapper.OmsCompanyAddressMapper.BaseResultMap"
                     columnPrefix="ca_">

        </association>
    </resultMap>

    <select id="selectById" resultMap="omsOrderReturnApplyResult">
        SELECT
            ra.*, ca.id ca_id,
                  ca.address_name ca_address_name,
                  ca.`name` ca_name,
                  ca.phone ca_phone,
                  ca.province ca_province,
                  ca.city ca_city,
                  ca.region ca_region,
                  ca.detail_address ca_detail_address
        FROM
            oms_order_return_apply ra
            LEFT JOIN oms_company_address ca ON ra.company_address_id = ca.id
        WHERE ra.id=#{id};
    </select>

sql查出来的数据要和resultmap中的colume相互对应，之后映射对用的bean, 如果resultmap中没有,bean就是空的。