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

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

<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>