sql优化

[pengzhistar]

我的sql语句如下
select *　from ｔ１　where to_char(kf_date,'yyyy-mm') = '2009-09' AND kf_caller NOT IN
(select kf_caller from ｔ１where to_char(kf_date,'yyyy-mm') = '2009-10' )

也就是本表查询 查找9月数据没在10月的

[cosio]

select *　from ｔ１　where to_char(kf_date,'yyyy-mm') = '2009-09' AND kf_caller NOT exists
(select kf_caller from ｔ１where to_char(kf_date,'yyyy-mm') = '2009-10' ) 

[pengzhistar]

... 1lou 无语

[cosio]

in 和 exists在效率是有差异!你可以先试试在说!

[cosio]

select aa.kf_caller FROM 
(select *　from t1 a　where to_char(kf_date,'yyyy-mm') = '2009-09') AA,
(select kf_caller from t1 b where to_char(kf_date,'yyyy-mm') = '2009-10' ) BB
WHERE AA.kf_caller=BB.kf_caller(+) and BB.kf_caller IS NULL

[iqlife]

[Quote=引用 3 楼 cosio 的回复:]
in 和 exists在效率是有差异!你可以先试试在说!
[/Quote]
UP

[pengzhistar]

真的吗 ？难道是8I的原因报错 ？ 还有你用的外关联 我早就试过了 不行 报错的！

[pengzhistar]

关联 好像是我丢了个括号！ 汗颜