<mapper namespace="com.example.demo.mapper.OrderMapper">

    <resultMap id="orderMap" type="com.example.demo.pojo.Order">
        <result property="id" column="id"></result>
        <result property="orderTime" column="orderTime"></result>
        <result property="total" column="total"></result>

        <association property="user" javaType="com.example.demo.pojo.User">
            <result property="id" column="uid"></result>
            <result property="username" column="username"></result>
        </association>
    </resultMap>


    <!--resultMap：手动来配置实体属性与表字段的映射关系-->
    <select id="findAll" resultMap="orderMap">
        select *
        from orders o,
             user u
        where o.uid = u.id
    </select>


</mapper>

<mapper namespace="com.example.demo.mapper.UserMapper">

    <resultMap id="userMap" type="com.example.demo.pojo.User">
        <result property="id" column="id"></result>
        <result property="username" column="username"></result>
        <result property="password" column="password"></result>
        <result property="birthday" column="birthday"></result>

        <collection property="orderList" ofType="com.example.demo.pojo.Order">
            <result property="id" column="oid"></result>
            <result property="orderTime" column="orderTime"></result>
            <result property="total" column="total"></result>
        </collection>
    </resultMap>


    <!--resultMap：手动来配置实体属性与表字段的映射关系-->
    <select id="findAll" resultMap="userMap">
        select *, o.id oid
        from user u
                 left join orders o on u.id = o.uid
    </select>


</mapper>