Mybatis_一对多关联查询

Posted 2020-11-03 lonske

person表对应orders表，一个人能下好几个订单。查询一个人下的所有订单。

有Orders类和Person类。

在Person类中加上一句：

private List<Orders> orderList;  并生成setter getter。

    <!--=======多表关联查询=======-->
    <!-- collection:集合的意思，property要和类中list名一样 ,ofType是集合中泛型也就是属性类型是什么-->
    <resultMap type="person" id="selectOrderByPersonIdRM">
        <id column = "person_id" property = "personId" />
        <result column = "name" property = "name" />
        <result column = "gender" property = "gender" />
        <result column = "person_addr" property = "personAddr" />
        <result column = "birthday" property = "birthday" />
        <collection property="orderList" ofType="xxx.x.model.Orders">
            <id column = "ORDER_ID" property = "orderId" />
            <result column = "PERSON_ID" property = "personId" />
            <result column = "TOTAL_PRICE" property = "totalPrice" />
            <result column = "ADDR" property = "addr" jdbcType="VARCHAR" />
        </collection>
    </resultMap>
    <select id = "selectOrderByPersonId" parameterType="int" resultMap="selectOrderByPersonIdRM">
        select * from person p, order o where p.PERSON_ID = o.person_id and p.PERSON_ID = #{id}
    </select>

    public void selectOrderByPersonId() {
        // 创建SqlSession
        SqlSession session = sessionFactory.openSession();
        try {
            Person person = session.selectOne("xxx.x.mapper.PersonTestMapper.deleteBatch", 1);
            System.out.println(person);
        } catch (Exception e) {
            e.printStackTrace();
            session.rollback();
        } finally {
            session.close();
        }
    }