mybatis 如何访问方法获取子节点

<!--查询组织下面的所有子组织-->

    <!--数据库先创建函数：如下-->

    <!--

    CREATE FUNCTION `getCatalogLst`(rootId INT)

     RETURNS varchar(1000)

    BEGIN

      DECLARE sTemp VARCHAR(1000);

       DECLARE sTempChd VARCHAR(1000);

      SET sTemp = '$';

      SET sTempChd =cast(rootId as CHAR);

       WHILE sTempChd is not null DO

         SET sTemp = concat(sTemp,',',sTempChd);

         SELECT group_concat(id) INTO sTempChd FROM exp_catalog where FIND_IN_SET(parent_id,sTempChd)>0;

    END WHILE;

    RETURN sTemp;

     END

-->

    <select id="getCatalogByParentId" resultType="ExpCatalogVO">

        SELECT * FROM EXP_CATALOG WHERE FIND_IN_SET(ID,getCatalogLst(#{parentId}));

    </select>