<!-- 查詢所有的訂單數(shù)據(jù) -->
    <!-- resultMap:填入配置的resultMap標(biāo)簽的id值 -->
    <select id="queryOrderAll" resultMap="orderResultMap">
        SELECT id, user_id,
        number,
        createtime, note FROM `order`
    </select>

<!-- resultMap最終還是要將結(jié)果映射到pojo上，type就是指定映射到哪一個pojo -->
    <!-- id：設(shè)置ResultMap的id -->
    <resultMap type="order" id="orderResultMap">
        <!-- 定義主鍵 ,非常重要。如果是多個字段,則定義多個id -->
        <!-- property：主鍵在pojo中的屬性名 -->
        <!-- column：主鍵在數(shù)據(jù)庫中的列名 -->
        <id property="id" column="id" />

        <!-- 定義普通屬性 -->
        <result property="userId" column="user_id" />
        <result property="number" column="number" />
        <result property="createtime" column="createtime" />
        <result property="note" column="note" />
    </resultMap>

<resultMap type="order" id="orderUserResultMap">
    <id property="id" column="id" />
    <result property="userId" column="user_id" />
    <result property="number" column="number" />
    <result property="createtime" column="createtime" />
    <result property="note" column="note" />

    <!-- association ：配置一對一屬性 -->
    <!-- property:order里面的User屬性名 -->
        <!-- javaType:屬性類型 -->
    <association property="user" javaType="user">
        <!-- id:聲明主鍵，表示user_id是關(guān)聯(lián)查詢對象的唯一標(biāo)識-->
        <id property="id" column="user_id" />
        <result property="username" column="username" />
        <result property="address" column="address" />
    </association>

</resultMap>

<!-- 一對一關(guān)聯(lián)，查詢訂單，訂單內(nèi)部包含用戶屬性 -->
<select id="queryOrderUserResultMap" resultMap="orderUserResultMap">
    SELECT
    o.id,
    o.user_id,
    o.number,
    o.createtime,
    o.note,
    u.username,
    u.address
    FROM
    `order` o
    LEFT JOIN `user` u ON o.user_id = u.id
</select>

@Test
public void testQueryOrderUserResultMap() {
    // mybatis和spring整合，整合之后，交給spring管理
    SqlSession sqlSession = this.sqlSessionFactory.openSession();
    // 創(chuàng)建Mapper接口的動態(tài)代理對象，整合之后，交給spring管理
    UserMapper userMapper = sqlSession.getMapper(UserMapper.class);

    // 使用userMapper執(zhí)行根據(jù)條件查詢用戶，結(jié)果封裝到Order類中
    List<Order> list = userMapper.queryOrderUserResultMap();
    for (Order o : list) {
        System.out.println(o);
    }
    // mybatis和spring整合，整合之后，交給spring管理
    sqlSession.close();
}

<resultMap type="user" id="userOrderResultMap">
    <id property="id" column="id" />
    <result property="username" column="username" />
    <result property="birthday" column="birthday" />
    <result property="sex" column="sex" />
    <result property="address" column="address" />

    <!-- 配置一對多的關(guān)系
        property：填寫pojo類中集合類類屬性的名稱
        javaType：填寫集合類型的名稱 
    -->
    <collection property="orders" javaType="list" ofType="order">
        <!-- 配置主鍵，是關(guān)聯(lián)Order的唯一標(biāo)識 -->
        <id property="id" column="oid" />
        <result property="number" column="number" />
        <result property="createtime" column="createtime" />
        <result property="note" column="note" />
    </collection>
</resultMap>

<!-- 一對多關(guān)聯(lián)，查詢訂單同時查詢該用戶下的訂單 -->
<select id="queryUserOrder" resultMap="userOrderResultMap">
    SELECT
    u.id,
    u.username,
    u.birthday,
    u.sex,
    u.address,
    o.id oid,
    o.number,
    o.createtime,
    o.note
    FROM
    `user` u
    LEFT JOIN `order` o ON u.id = o.user_id
</select>