--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 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,速度也会越来越慢哦!) 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; |
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