--1:無ORDER BY排序的寫法。(效率最高) ­

--(經過測試，此方法成本最低，只嵌套一層，速度最快！即使查詢的數據量再大，也幾乎不受影響，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 &shy;

WHERE TABLE_ALIAS.ROWNO >= 10; &shy;

&shy;

--2:有ORDER BY排序的寫法。(效率最高) &shy;

--(經過測試，此方法隨著查詢范圍的擴大，速度也會越來越慢哦！) &shy;

SELECT * &shy;

FROM (SELECT TT.*, ROWNUM AS ROWNO &shy;

FROM (Select t.* &shy;

from k_task T &shy;

where flight_date between to_date('20060501', 'yyyymmdd') and &shy;

to_date('20060531', 'yyyymmdd') &shy;

ORDER BY FACT_UP_TIME, flight_no) TT &shy;

WHERE ROWNUM <= 20) TABLE_ALIAS &shy;

where TABLE_ALIAS.rowno >= 10; &shy;

&shy;

--3:無ORDER BY排序的寫法。(建議使用方法1代替) &shy;

--(此方法隨著查詢數據量的擴張，速度會越來越慢哦！) &shy;

SELECT * &shy;

FROM (Select ROWNUM AS ROWNO, T.* &shy;

from k_task T &shy;

where Flight_date between to_date('20060501', 'yyyymmdd') and &shy;

to_date('20060731', 'yyyymmdd')) TABLE_ALIAS &shy;

WHERE TABLE_ALIAS.ROWNO <= 20 &shy;

AND TABLE_ALIAS.ROWNO >= 10; &shy;

--TABLE_ALIAS.ROWNO  between 10 and 100; &shy;

&shy;

--4:有ORDER BY排序的寫法.(建議使用方法2代替) &shy;

--(此方法隨著查詢范圍的擴大，速度會越來越慢哦！) &shy;

SELECT * &shy;

FROM (SELECT TT.*, ROWNUM AS ROWNO &shy;

FROM (Select * &shy;

from k_task T &shy;

where flight_date between to_date('20060501', 'yyyymmdd') and &shy;

to_date('20060531', 'yyyymmdd') &shy;

ORDER BY FACT_UP_TIME, flight_no) TT) TABLE_ALIAS &shy;

where TABLE_ALIAS.rowno BETWEEN 10 AND 20; &shy;

&shy;

&shy;

--5另類語法。(有ORDER BY寫法） &shy;

--(語法風格與傳統(tǒng)的SQL語法不同，不方便閱讀與理解，為規(guī)范與統(tǒng)一標準，不推薦使用。) &shy;

With partdata as( &shy;

SELECT ROWNUM AS ROWNO, TT.*  FROM (Select * &shy;

from k_task T &shy;

where flight_date between to_date('20060501', 'yyyymmdd') and &shy;

to_date('20060531', 'yyyymmdd') &shy;

ORDER BY FACT_UP_TIME, flight_no) TT &shy;

WHERE ROWNUM <= 20) &shy;

Select * from partdata where rowno >= 10; &shy;

&shy;

--6另類語法 。(無ORDER BY寫法） &shy;

With partdata as( &shy;

Select ROWNUM AS ROWNO, T.* &shy;

From K_task T &shy;

where Flight_date between to_date('20060501', 'yyyymmdd') and &shy;

To_date('20060531', 'yyyymmdd') &shy;

AND ROWNUM <= 20) &shy;

Select * from partdata where Rowno >= 10; &shy;

-

更多信息請查看IT技術專欄