[20150205]分析函数ntile.txt

[20150205]分析函数ntile.txt

--同事要做一个批量修改操作,修改时间太长,需要分段修改并且提交.
--想到可以按照rowid分段.

--google 一些例子,做一些记录:

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

--这样就可以实现3段rowid.