6-1 店铺信息编辑之Dao层的实现_商家dao层怎么写-优快云博客

本文链接：https://blog.youkuaiyun.com/weixin_40703303/article/details/89387727

本文详细介绍了MyBatis框架中resultMap的使用方法，包括如何定义与外键关联的resultMap，以及如何在<select>标签中引用resultMap进行复杂查询。通过具体示例，展示了如何将数据库字段映射到Java对象属性，实现对象关系映射(ORM)。

1、编写Dao接口

2、编写Dao的实现

做查询

首先要编写resultMap（输出结果），<id>是主键，<result>是数据库字段和属性的对应，<association>是外键里的属性

在<select>标签中resultMap 引用的就是上面的id

<mapper namespace="com.imooc.o2o.dao.ShopDao">
    <resultMap type="com.imooc.o2o.entity.Shop" id="shopMap">
    	<id column="shop_id" property="shopId"/>
    	<result column="shop_name" property="shopName"/>
    	<result column="shop_desc" property="shopDesc"/>
    	<result column="shop_addr" property="shopAddr"/>
    	<result column="phone" property="phone"/>
    	<result column="priority" property="priority"/>
    	<result column="create_time" property="createTime"/>
    	<result column="last_edit_time" property="lastEditTime"/>
    	<result column="enable_status" property="enableStatus"/>
    	<result column="advice" property="advice"/>
    	<association property="area" column="area_id" javaType="com.imooc.o2o.entity.Area">
    		<id column="area_id" property="areaId"/>
    		<result column="area_name" property="areaName"/>
    	</association>
    	<association property="shopCategory" column="shop_category_id" javaType="com.imooc.o2o.entity.ShopCategory">
    		<id column="shop_category_id" property="shopCategoryId"/>
    		<result column="shop_category_name" property="shopCategoryName"/>
    	</association>
    	<association property="owner" column="user_id" javaType="com.imooc.o2o.entity.PersonInfo">
    		<id column="user_id" property="userId"/>
    		<result column="name" property="name"/>
    	</association>
    </resultMap>
   <select id="queryByShopId" resultMap="shopMap" parameterType="Long">
   	SELECT 
   		s.shop_id,
   		s.shop_name,
   		s.shop_desc,
   		s.shop_addr,
   		s.phone,
		s.shop_img,
		s.priority,
		s.create_time,
		s.last_edit_time,
		s.enable_status,
		s.advice,
		a.area_id,
		a.area_name,
		sc.shop_category_id,
		sc.shop_category_name
		FROM
		tb_shop s,
		tb_area a,
		tb_shop_category sc
		WHERE
		s.area_id=a.area_id
		AND
		s.shop_category_id=sc.shop_category_id
		AND
		s.shop_id=#{shopId}
   </select>

3、测试