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HomeDatabaseMysql Tutorialoracle分页查询sql原理与语句

很多朋友使用多了mysql limit进行分页到了oracle中就不知道如何写分页了,其实oracle分页与mssql分页很像的,下面我来给大家介绍oracle分页语句。

很多朋友使用多了mysql limit进行分页到了oracle中就不知道如何写分页了,其实oracle分页与mssql分页很像的,下面我来给大家介绍oracle分页语句。

最简单使用方法

 代码如下 复制代码

t2.*
from (select rownum r,t1.* from youtable t1 where rownum) t2
where t2.r>?

小于最大的,大于最小的,就是你需要的条数.如果你取40-50条之间的

查询格式:

 代码如下 复制代码

SELECT * FROM
(
SELECT A.*, ROWNUM RN
FROM (SELECT * FROM TABLE_NAME) A
WHERE ROWNUM )
WHERE RN >= 21

其中最内层的查询SELECT * FROM TABLE_NAME表示不进行翻页的原始查询语句。ROWNUM = 21控制分页查询的每页的范围。
上面给出的这个分页查询语句,在大多数情况拥有较高的效率。分页的目的就是控制输出结果集大小,将结果尽快的返回。在上面的分页查询语句中,这种考虑主要体现在WHERE ROWNUM 选择第21到40条记录存在两种方法,一种是上面例子中展示的在查询的第二层通过ROWNUM

 代码如下 复制代码

SELECT * FROM

(
SELECT A.*, ROWNUM RN
FROM (SELECT * FROM TABLE_NAME) A
)
WHERE RN BETWEEN 21 AND 40

后来发现数据越大就查询越慢了,后来得出一些测试结果分享给大家。

--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!)

 代码如下 复制代码
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 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,速度也会越来越慢哦!)

 代码如下 复制代码
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 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,速度会越来越慢哦!)

 代码如下 复制代码
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    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,速度会越来越慢哦!)

 代码如下 复制代码
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)
--(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。)

 代码如下 复制代码
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     Select * from partdata where rowno >= 10;

--6另类语法 。(无ORDER BY写法)

 代码如下 复制代码

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     Select * from partdata where Rowno >= 10;   

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