Mybatis多对一

一、在实体类上添加对应的属性,并添加set、get方法

//    多一对关联,在多的一方只有一的实体
    private Goods goods;

二、xml文件中编写sql语句

<resultMap id="goodsDetailMap" type="com.itlaoqi.mybatis.entity.GoodsDetail">
        <id property="gdId" column="gd_id"/>
        <!--在查询时每得到一个goods_detail表记录,便将goods_id字段值带入到
        goods.findById SQL的 select * from t_goods where goods_id = goods_id字段值,获取Goods对象
        并将其赋值给GoodsDetail对象的goods属性-->
        <association property="goods" select="goods.findById" column="goods_id"/>
    </resultMap>
    <select id="selectManyToOne" resultMap="goodsDetailMap">
      select * from t_goods_detail limit 0,10
    </select>

对应的单一查询语句为:

 <select id="findById" parameterType="Integer" resultType="com.itlaoqi.mybatis.entity.Goods" useCache="false">

        select * from t_goods where goods_id = #{value}
    </select>