<resultMap type="Account"id="accountMap"autoMapping="true">
        <id column ="id" property="id"/> 
        <result column ="opt_time" property="optTime"/>
        <result column ="create_time" property="createTime"/>
        <result column ="update_time" property="updateTime"/>
        <association property ="item" javaType="Item">
              <result column ="item_code" property="code"/>
              <result column ="item_name" property="name"/>
              <result column ="item_model" property="model"/>
              <result column ="unit" property="unit"/>
        </association >
</resultMap >