mysql自建递归查询函数

BEGIN
DECLARE oTemp VARCHAR(4000);
DECLARE oTempChild VARCHAR(4000);

SET oTemp = '';
SET oTempChild = CAST(orgid AS CHAR);

WHILE oTempChild IS NOT NULL
DO
SET oTemp = CONCAT(oTemp,',',oTempChild);
SELECT GROUP_CONCAT(au_id) INTO oTempChild FROM admin_user WHERE FIND_IN_SET(au_parent_id,oTempChild) > 0;
END WHILE;
RETURN oTemp;
END