常用的Oracle查询语句

1.无ORDER BY排序的写法。(效率最高)

经过测试，此方法成本最低，只嵌套一层，速度最快！即使查询的数据量再大，也几乎不受影响，速度依然！

sql语句如下：

SELECT *

        FROM (Select ROWNUM AS ROWNO, T.*

       from k_task T

      where Flight_date between to_date('20060501', 'yyyymmdd') and

       to_date('20060731', 'yyyymmdd')

       AND ROWNUM <= 20) TABLE_ALIAS

WHERE TABLE_ALIAS.ROWNO >= 10;

2.有ORDER BY排序的写法。(效率最高)

经过测试，此方法随着查询范围的扩大，速度也会越来越慢！ 

SELECT *

       FROM (SELECT TT.*, ROWNUM AS ROWNO

         FROM (Select t.*

         from k_task T

        where flight_date between to_date('20060501', 'yyyymmdd') and

       to_date('20060531', 'yyyymmdd')

      ORDER BY FACT_UP_TIME, flight_no) TT

WHERE ROWNUM <= 20) TABLE_ALIAS

where TABLE_ALIAS.rowno >= 10;

3.无ORDER BY排序的写法。(建议使用方法1代替)

此方法随着查询数据量的扩张，速度会越来越慢！  

    

SELECT *

      FROM (Select ROWNUM AS ROWNO, T.*

      from k_task T

       where Flight_date between to_date('20060501', 'yyyymmdd') and

          to_date('20060731', 'yyyymmdd')) TABLE_ALIAS

         WHERE TABLE_ALIAS.ROWNO <= 20

          AND TABLE_ALIAS.ROWNO >= 10;

TABLE_ALIAS.ROWNO between 10 and 100;

4.有ORDER BY排序的写法.(建议使用方法2代替)

此方法随着查询范围的扩大，速度也会越来越慢！      

 

SELECT *

FROM (SELECT TT.*, ROWNUM AS ROWNO

FROM (Select *

from k_task T

where flight_date between to_date('20060501', 'yyyymmdd') and

to_date('20060531', 'yyyymmdd')

ORDER BY FACT_UP_TIME, flight_no) TT) TABLE_ALIAS

where TABLE_ALIAS.rowno BETWEEN 10 AND 20;

5.另类语法。(有ORDER BY写法）

该语法风格与传统的SQL语法不同，不方便阅读与理解，为规范与统一标准，不推荐使用。此处贴出代码供大家参考之用。

 

With partdata as(

SELECT ROWNUM AS ROWNO, TT.* FROM (Select *

from k_task T

where flight_date between to_date('20060501', 'yyyymmdd') and

to_date('20060531', 'yyyymmdd')

ORDER BY FACT_UP_TIME, flight_no) TT

WHERE ROWNUM <= 20)

Select * from partdata where rowno >= 10;

6.另类语法 。(无ORDER BY写法）

With partdata as(

Select ROWNUM AS ROWNO, T.*

From K_task T

where Flight_date between to_date('20060501', 'yyyymmdd') and

To_date('20060531', 'yyyymmdd')

AND ROWNUM <= 20)

Select * from partdata where Rowno >= 10;