[20150205]分析函式ntile.txt

[20150205]分析函式ntile.txt

--同事要做一個批次修改操作,修改時間太長,需要分段修改並且提交.
--想到可以按照rowid分段.

--google 一些例子,做一些記錄:

SELECT MIN (a), MAX (a), b
    FROM (SELECT ROWID a, NTILE (3) OVER (ORDER BY ROWID) b FROM emp)
GROUP BY b
ORDER BY b;

MIN(A)             MAX(A)                      B
------------------ ------------------ ----------
AAAR3xAAEAAAACXAAA AAAR3xAAEAAAACXAAE          1
AAAR3xAAEAAAACXAAF AAAR3xAAEAAAACXAAJ          2
AAAR3xAAEAAAACXAAK AAAR3xAAEAAAACXAAN          3

--這樣就可以實現3段rowid.