2009年5月19日星期二

mget一次传送多个文件都要回答y

使用ftp –i <ip>
或者prompt命令关闭Interactive mode

修改命令行窗口的Code Page

chcp 950 中文繁体big5
chcp 936 中文简体gbk

Sorting Multilingual Data

Oracle9i之前,中文是按照二进制编码进行排序的。在oracle9i中新增了按照拼音、部首、笔画排序功能。

1、设置NLS_SORT参数值
      SCHINESE_RADICAL_M 按照部首(第一顺序)、笔划(第二顺序)排序
      SCHINESE_STROKE_M 按照笔划(第一顺序)、部首(第二顺序)排序
      SCHINESE_PINYIN_M 按照拼音排序

2、Session级别的设置,修改ORACLE字段的默认排序方式:
      按拼音:alter session set nls_sort = SCHINESE_PINYIN_M;
      按笔画:alter session set nls_sort = SCHINESE_STROKE_M;
      按偏旁:alter session set nls_sort = NLS_SORT=SCHINESE_RADICAL_M;

3、语句级别设置排序方式:
      按照笔划排序
      select * from dept order by nlssort(name,'NLS_SORT=SCHINESE_STROKE_M');
      按照部首排序
      select * from dept order by nlssort(name,'NLS_SORT=SCHINESE_RADICAL_M');
      按照拼音排序,此为系统的默认排序方式
      select * from dept order by nlssort(name,'NLS_SORT=SCHINESE_PINYIN_M');

4、修改系统参数(数据库所在操作系统):
      set NLS_SORT=SCHINESE_RADICAL_M ;export NLS_SORT (sh)
       setenv NLS_SORT SCHINESE_RADICAL_M (csh)
      HKLC\SOFTWARE\ORACLE\home0\NLS_SORT (win注册表)

Oracle 官方说明

NLS_SORT NLS_SORT specifies the collating sequence for ORDER BY queries. NLS_COMP NLS_COMP specifies the collation behavior of the database session.

Property

Description

Parameter type

String

Syntax

NLS_SORT = { BINARY | linguistic_definition }

Default value

Derived from NLS_LANGUAGE

Modifiable

ALTER SESSION

Range of values

BINARY or any valid linguistic definition name

  • If the value is BINARY, then the collating sequence for ORDER BY queries is based on the numeric value of characters (a binary sort that requires less system overhead).
  • If the value is a named linguistic sort, sorting is based on the order of the defined linguistic sort. Most (but not all) languages supported by the NLS_LANGUAGE parameter also support a linguistic sort with the same name.

    Note:

    Setting NLS_SORT to anything other than BINARY causes a sort to use a full table scan, regardless of the path chosen by the optimizer. BINARY is the exception because indexes are built according to a binary order of keys. Thus the optimizer can use an index to satisfy the ORDER BY clause when NLS_SORT is set to BINARY. If NLS_SORT is set to any linguistic sort, the optimizer must include a full table scan and a full sort in the execution plan.

         You must use the NLS_SORT operator with comparison operations if you want the linguistic sort behavior.

Property

Description

Parameter type

String

Syntax

NLS_COMP = { BINARY | LINGUISTIC | ANSI }

Default value

BINARY

Modifiable

ALTER SESSION

Basic

No

Values:

  • BINARY

Normally, comparisons in the WHERE clause and in PL/SQL blocks is binary unless you specify the NLSSORT function.

  • LINGUISTIC

Comparisons for all SQL operations in the WHERE clause and in PL/SQL blocks should use the linguistic sort specified in the NLS_SORT parameter. To improve the performance, you can also define a linguistic index on the column for which you want linguistic comparisons.

  • ANSI

A setting of ANSI is for backwards compatibility; in general, you should set NLS_COMP to LINGUISTIC

2009年5月18日星期一

FLT_EPSILON

FLT_EPSILON
This is the minimum positive floating point number of type float such that 1.0 + FLT_EPSILON != 1.0 is true. It's supposed to be no greater than 1E-5.

2009年5月13日星期三

《潜伏》中的一段对话

        余则成:是觉得无路可走了吗?
晚秋:(哭,点头)
余:其实你面前有一条通往未来的路啊。(秋流泪摇头)值得你活下去。那一路很美好,就像你的诗歌一样。怎么会觉得无路可走了呢?
秋:你愿意娶我吗?
余:比娶你更美好。还多了一份自由。你不是最向往自由吗?
秋:(点头)
余:你也知道我的身份了。你愿意去吗?
秋:那我就再也见不到你了。
余:那儿有很多人都像我一样。那是另一个世界,好地方,好风光。你那么年轻,那么漂亮,可以选择的。你想想,晚秋,你站在一列雄壮的队伍里,迈着大步,高唱着战歌,去改变整个中国,那是什么气势?一个小小的余则成,就是路边的一个送行者,你看见了他,他看见了你,你们挥挥手就过去了。再往前就是更有意义的生活。沮丧吗?无非就是一个小布尔乔亚的无病呻吟。留恋它就是一种高度近视。有时候看得远一点,不就什么都有了么。包括爱。