select t_id,r from (select A.t_id,rownum r from (selectt_id from bnews where t_state=1 and t_cate=67and t_p_id='0' order by t_order desc ) A where rownum1
内两层的查询很快的
select A.t_id,rownum r from (selectt_id from bnews where t_state=1 and t_cate=67and t_p_id='0' order by t_order desc ) A where rownum1
执行计划
Object owner |Object name | Cost Cardinality | Bytes |IO cost
SELECT STATEMENT, GOAL = CHOOSE
16
8
360
16
VIEW
JHGXS
16
8
360
SORT ORDER BY
16
8
256
16
COUNT STOPKEY
VIEW
JHGXS
11
8
256
SORT ORDER BY STOPKEY
11
8
824
11
TABLE ACCESS BY INDEX ROWID
JHGXS
bnews
6
8
824
6
INDEX RANGE SCAN
JHGXS
bnews_CATE
31875
2
7.89s
按道理数据在内两层都取出来了.应该很快呀.
[ 本帖最后由 xiaotest 于 2010-8-28 11:12 编辑 ]
select t_id,r from (select A.t_id,rownum r from
(selectt_id from bnews where t_state=1 and t_cate=67
and t_p_id='0' order by t_order desc ) A
where rownum1