mybatis association 映射：同文件中的使用

<resultMap type="User" id="UserResult">

<result property="sUserID" column="sUserID"/>
<result property="sUserName" column="sUserName"/>

<result property="sPassword" column="sPassword"/>

<association property="userRoleString" column="sUserID" select="selectUserRoles"></association>

</resultMap>

<select id="selectById" parameterType = "String" resultMap="UserResult">
select * from po_user
where sUserID = #{sUserID}
</select>

<select id="selectUserRoles" parameterType = "String" resultType="String">
SELECT  sRoleName 
FROM po_userrole 
WHERE sUserID = #{sUserID}
</select>