oracle语句使用经验

SELECT
FROM (SELECT A1. ，ROWNUM RN
FROM (SELECT H.*
FROM TBC_ADOWNBLK_HIST H
WHERE 1 = 1
ORDER BY adownblkid ASC) A1
WHERE ROWNUM <= 10)
WHERE RN >= 1
想排序必须按这种写法

--根据不同字典值去加‘前缀’
方法一
select CASE
WHEN dict_code = 'YYPZ' THEN '0' || CODE
ELSE '1' || CODE end as code,
name as name
from MSTB_BDS_DATA
where (dict_code = 'VOICEOTHERTYPE' or dict_code = 'YYPZ')
and record_state = '1'
方法二
(select '0'||CODE code,NAME from MSTB_BDS_DATA d where d.dict_code='YYPZ' and record_state = '1' ) uNIOn all (select '1'||CODE code,NAME from MSTB_BDS_DATA d where d.dict_code='VOICEOTHERTYPE' and record_state = '1')