MyBatis映射文件resultMap元素中使用多个association

现在有一张订单表t_stockorder，其拥有id、code、client_id、merchandise_id、merchandise_number、order_date、operator_id这些字段，其中client_id关联t_client表中code字段，merchandise_id关联t_merchandise表的code字段，operator_id关联t_employee表的code字段。

现在要通过SQL语句将订单表中t_stockorder的数据全部查询出来，SQL语句如下所示：

select so.id, so.code, c.name cname, m.name mname,
        so.merchandise_number,
        so.order_date, e.name ename
        from
        inventory.t_stockorder so
        inner join
        inventory.t_client c on c.code = so.client_id
        inner join
        inventory.t_merchandise m on m.code = so.merchandise_id
        inner join
        inventory.t_employee e on e.code = so.operator_id

现在要在mapper映射文件中添加动态Sql语句，一般情况下映射文件中的resultMap元素中只可以有一个association，那如何添加多个association到resultMap中呢？正确代码如下图所示：

<resultMap id="StockorderMap" type="com.lwz.entity.Stockorder">
        <id property="id" column="id" />
        <result property="code" column="code" />
        <result property="merchandiseNumber" column="merchandise_number" />
        <result property="orderDate" column="order_date" />
        <association property="client" javaType="Client" resultMap="ClientResultMap"></association>
        <association property="merchandise" javaType="Merchandise" resultMap="MerchandiseResultMap"></association>
        <association property="employee" javaType="Employee" resultMap="EmployeeResultMap"></association>
    </resultMap>
    <resultMap id="ClientResultMap" type="com.lwz.entity.Client">
        <id property="code" column="code" />
        <result property="name" column="cname" />
    </resultMap>
    <resultMap id="MerchandiseResultMap" type="com.lwz.entity.Merchandise">
        <id property="code" column="code" />
        <result property="name" column="mname" />
    </resultMap>
    <resultMap id="EmployeeResultMap" type="com.lwz.entity.Employee">
        <id property="code" column="code" />
        <result property="name" column="ename" />
    </resultMap>

    <!--通过实体作为筛选条件查询-->
    <select id="queryAll" resultMap="StockorderMap">
        select so.id, so.code, c.name cname, m.name mname,
        so.merchandise_number,
        so.order_date, e.name ename
        from
        inventory.t_stockorder so
        inner join
        inventory.t_client c on c.code = so.client_id
        inner join
        inventory.t_merchandise m on m.code = so.merchandise_id
        inner join
        inventory.t_employee e on e.code = so.operator_id
        <where>
            <if test="id != null">
                and id = #{id}
            </if>
            <if test="code != null and code != ''">
                and so.code = #{code}
            </if>
            <if test="client != null">
                and client_id = #{client.code}
            </if>
            <if test="merchandise != null">
                and merchandise_id = #{merchandise.code}
            </if>
            <if test="merchandiseNumber != null">
                and merchandise_number = #{merchandiseNumber}
            </if>
            <if test="orderDate != null">
                and order_date = #{orderDate}
            </if>
            <if test="employee != null">
                and operator_id = #{employee.code}
            </if>
        </where>
    </select>