Oracle的分页查询

--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！)

SELECT *
  FROM (SELECT ROWNUM AS rowno, t.*
          FROM emp t
         WHERE hire_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，速度也会越来越慢哦！)

SELECT *
  FROM (SELECT tt.*, ROWNUM AS rowno
          FROM (  SELECT t.*
                    FROM emp t
                   WHERE hire_date BETWEEN TO_DATE ('20060501', 'yyyymmdd')
                                       AND TO_DATE ('20060731', 'yyyymmdd')
                ORDER BY create_time DESC, emp_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，速度会越来越慢哦！)

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，速度会越来越慢哦！)

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。)

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;