What's NLS_LANG and usage
URL:http://download.oracle.com/docs/html/B13805_02/gblsupp.htm#BCEEEJGF
C Oracle Database Globalization Support
This appendix describes these Globalization Support topics:
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About NLS_LANG Parameters
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Commonly Used Values for NLS_LANG
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NLS_LANG Settings in MS-DOS Mode and Batch Mode
C.1 About NLS_LANG Parameters
Oracle provides Globalization Support that enables users to interact with a database in their own language, as defined by the NLS_LANG parameter. When you install Oracle Database components, Oracle Universal Installer sets the NLS_LANG parameter in the registry.
The locale setting of your operating system determines the value of the NLS_LANG parameter at installation. Table C-1 lists the operating system locale and NLS_LANG value mappings.
The NLS_LANG parameter is stored in the registry under the HKEY_LOCAL_MACHINE/SOFTWARE/ORACLE/HOME ID /NLS_LANG subkey, where ID is the unique number identifying the Oracle home.
The NLS_LANG parameter uses the following format:
NLS_LANG = LANGUAGE_TERRITORY . CHARACTER_SET
where:
| Parameter | Description |
|---|---|
LANGUAGE |
Specifies the language and conventions for displaying messages, day name, and month name. |
TERRITORY |
Specifies the territory and conventions for calculating week and day numbers. |
CHARACTER_SET |
Controls the character set used for displaying messages. |
| See Also:
|
C.2 Commonly Used Values for NLS_LANG
Table C-1 lists commonly used NLS_LANG values for various operating system locales:
Table C-1 NLS_LANG Parameter Values
| Operating System Locale | NLS_LANG Value |
|---|---|
| Arabic (U.A.E.) | ARABIC_UNITED ARAB EMIRATES.AR8MSWIN1256 |
| Bulgarian | BULGARIAN_BULGARIA.CL8MSWIN1251 |
| Catalan | CATALAN_CATALONIA.WE8MSWIN1252 |
| Chinese (PRC) | SIMPLIFIED CHINESE_CHINA.ZHS16GBK |
| Chinese (Taiwan) | TRADITIONAL CHINESE_TAIWAN.ZHT16MSWIN950 |
| Croatian | CROATIAN_CROATIA.EE8MSWIN1250 |
| Czech | CZECH_CZECH REPUBLIC.EE8MSWIN1250 |
| Danish | DANISH_DENMARK.WE8MSWIN1252 |
| Dutch (Netherlands) | DUTCH_THE NETHERLANDS.WE8MSWIN1252 |
| English (United Kingdom) | ENGLISH_UNITED KINGDOM.WE8MSWIN1252 |
| English (United States) | AMERICAN_AMERICA.WE8MSWIN1252 |
| Estonian | ESTONIAN_ESTONIA.BLT8MSWIN1257 |
| Finnish | FINNISH_FINLAND.WE8MSWIN1252 |
| French (Canada) | CANADIAN FRENCH_CANADA.WE8MSWIN1252 |
| French (France) | FRENCH_FRANCE.WE8MSWIN1252 |
| German (Germany) | GERMAN_GERMANY.WE8MSWIN1252 |
| Greek | GREEK_GREECE.EL8MSWIN1253 |
| Hebrew | HEBREW_ISRAEL.IW8MSWIN1255 |
| Hungarian | HUNGARIAN_HUNGARY.EE8MSWIN1250 |
| Icelandic | ICELANDIC_ICELAND.WE8MSWIN1252 |
| Indonesian | INDONESIAN_INDONESIA.WE8MSWIN1252 |
| Italian (Italy) | ITALIAN_ITALY.WE8MSWIN1252 |
| Japanese | JAPANESE_JAPAN.JA16SJIS |
| Korean | KOREAN_KOREA.KO16MSWIN949 |
| Latvian | LATVIAN_LATVIA .BLT8MSWIN1257 |
| Lithuanian | LITHUANIAN_LITHUANIA.BLT8MSWIN1257 |
| Norwegian | NORWEGIAN_NORWAY.WE8MSWIN1252 |
| Polish | POLISH_POLAND.EE8MSWIN1250 |
| Portuguese (Brazil) | BRAZILIAN PORTUGUESE_BRAZIL.WE8MSWIN1252 |
| Portuguese (Portugal) | PORTUGUESE_PORTUGAL.WE8MSWIN1252 |
| Romanian | ROMANIAN_ROMANIA.EE8MSWIN1250 |
| Russian | RUSSIAN_CIS.CL8MSWIN1251 |
| Slovak | SLOVAK_SLOVAKIA.EE8MSWIN1250 |
| Spanish (Spain) | SPANISH_SPAIN.WE8MSWIN1252 |
| Swedish | SWEDISH_SWEDEN.WE8MSWIN1252 |
| Thai | THAI_THAILAND.TH8TISASCII |
| Spanish (Mexico) | MEXICAN SPANISH_MEXICO.WE8MSWIN1252 |
| Spanish (Venezuela) | LATIN AMERICAN SPANISH_VENEZUELA.WE8MSWIN1252 |
| Turkish | TURKISH_TURKEY.TR8MSWIN1254 |
| Ukrainian | UKRAINIAN_UKRAINE.CL8MSWIN1251 |
| Vietnamese | VIETNAMESE_VIETNAM.VN8MSWIN1258 |
C.3 NLS_LANG Settings in MS-DOS Mode and Batch Mode
Before you can use Oracle utilities such as SQL*Plus, SQL Loader, Import, and Export in MS-DOS mode, make sure that you have set the character set field of the NLS_LANG parameter for the session to the correct value.
This is required because MS-DOS mode uses, with a few exceptions, a different character set (or code-page) from Windows (ANSI code-page), and the default Oracle home NLS_LANG parameter in the registry is always set to the appropriate Windows code-page. If you do not set the NLS_LANG parameter for the MS-DOS mode session correctly, incorrect character conversion can corrupt error messages and data.
For Japanese, Korean, Simplified Chinese, and Traditional Chinese, the MS-DOS code-page is identical to the ANSI code-page. In this case, you do not need to set the NLS_LANG parameter in MS-DOS mode.
Similarly, in batch mode, set the correct character set value of NLS_LANG by inserting a SET NLS_LANG command at the start of the batch procedure, according to the character set of the files to be processed in the procedure.
Table C-2 lists the Oracle character sets that correspond to the MS-DOS mode for various operating system locales:
Table C-2 Oracle Character Sets for Operating System Locales
| Operating System Locale | Character Set |
|---|---|
| Arabic | AR8ASMO8X |
| Catalan | WE8PC850 |
| Chinese (PRC) | ZHS16GBK |
| Chinese (Taiwan) | ZHT16MSWIN950 |
| Czech | EE8PC852 |
| Danish | WE8PC850 |
| Dutch | WE8PC850 |
| English (United Kingdom) | WE8PC850 |
| English (United States) | US8PC437 |
| Finnish | WE8PC850 |
| French | WE8PC850 |
| German | WE8PC850 |
| Greek | EL8PC737 |
| Hungarian | EE8PC852 |
| Italian | WE8PC850 |
| Japanese | JA16SJIS |
| Korean | KO16MSWIN949 |
| Norwegian | WE8PC850 |
| Polish | EE8PC852 |
| Portuguese | WE8PC850 |
| Romanian | EE8PC852 |
| Russian | RU8PC866 |
| Slovak | EE8PC852 |
| Slovenian | EE8PC852 |
| Spanish | WE8PC850 |
| Swedish | WE8PC850 |
| Turkish | TR8PC857 |
| See Also: " Globalization Support in the Directory" in Oracle Internet Directory Administrator's Guide for Oracle Internet Directory Globalization Support issues and requiredNLS_LANG environment variables for the various components and tools in an Oracle Internet Directory environment |
NLS_LANG = LANGUAGE_TERRITORY . CHARACTER_SET
2. To check session NLS session parameters, note this doesn’t return the characterset set by NLS_LANG
SELECT * FROM NLS_SESSION_PARAMETERS;
SELECT USERENV ('language') FROM DUAL;
To find the NLS_LANG of your database one can run the following SQL:
SQL> SELECT * from NLS_DATABASE_PARAMETERS WHERE parameter IN ( 'NLS_LANGUAGE', 'NLS_TERRITORY', 'NLS_CHARACTERSET');
PARAMETER VALUE
—————————— —————————————-
NLS_LANGUAGE AMERICAN
NLS_TERRITORY AMERICA
NLS_CHARACTERSET WE8MSWIN1252
To get the possible value for language, territory and characterset you can check the view V$NLS_VALID_VALUES.
– parameter – possible values LANGUAGE, TERRITORY, CHARACTERSET
SELECT parameter, value FROM V$NLS_VALID_VALUES;
To change the client language
export NLS_LANG=BELGIUM_.WE8ISO8859P1
To change the client territory
export NLS_LANG=_BELGIUM.WE8ISO8859P1
To change the client characterset
export NLS_LANG=.AL32UTF8
3.setup in shell scripts:
NLS_LANG='english_united kingdom.we8iso8859p1'; export NLS_LANG
4.其他：
Oracle NLS_LANG小结
很奇怪为什么能成功导入，做了个是试验：
创建了一个Test表，包含日文字符。
导出两次，NLS_LANG分别是AMERICAN_AMERICA.US7ASCII和AMERICAN_AMERICA.JA16SJIS，对比两次导出的dump文件，发现只有文件头不一样，其余部分基本一致，尤其是建表和插入的数据二进制部分完全一样。NLS_LANG的设置可能不会影响 dump文件的编码。通过查询Oracle网站得到这样的一句话
In Oracle9i the Export utility always exports user data, including Unicode data, in the character set of the database. The Import utility automatically converts the data to the character set of the target database.
也就是说，dump文件的数据的编码和源数据库的相同，不管Client的NLS_LANG如何设置。如果源数据库的字符集和目标数据库的字符集不一致，import时会自动转换。当然在不一致的情况下，源数据库的字符集一定要是目标数据库的子集。再查了下《循序渐进Oracle》，书中关于导入导出的例子使用的Oracle 8i，应该是作者偷懒把上一版的内容直接拿过来没更新。
另外再Oracle提供的关于NLS_LANG FAQ也列出了几条对NLS_LANG误解：
“NLS_LANG和数据库的字符集一样或许是正确的，但是经常是不对的。不要认为NLS_LANG必须和数据库的字符集一样，这经常是错的。” 《循序渐进Oracle》中说NLS_LANG一样的话可以提高性能，因为不需要字符集的转换。其实这样的转换不时发生在Server端，Client端转换完成后传递给Server端。我觉得，只要NLS_LANG是Server的字符集的子集就可以。
“NLS_LANG的字符集设置不会更改Client端的字符集。它只是用来告诉Oracle你在Client端使用什么字符集，你不能通过设置NLS_LANG去影响Client的字符集”。而且如果Client端的字符集和NLS_LANG不兼容，会导致数据库乱码。
“如果你不在Client端设置NLS_LANG，那么默认会使用Server的NLS_LANG设置，这是错的。如果Oracle在安装时没有设置NLS_LANG，那么NLS_LANG不会另外再设置，而是使用默认值：AMERICAN_AMERICA.US7ASCII。语言是 AMERICAN，区域是AMERICA，字符集US7ASCII”
“设置NLS_LANG的LANGUAGE 和 TERRITORY部分不会影响存储在数据库的字符。将NLS_LANG设置为JAPANESE_JAPAN.WE8MSWIN1252不会允许你存储日文。因为WE8MSWIN1252字符集不支持日文。但是设置成AMERICAN_AMERICA.JA16SJIS会允许你存储日文，假设你输入的字符是JA16SJIS，并且数据库的字符集也支持日文（如UTF8或者JA16SJIS）”
SELECT USERENV ('language') FROM DUAL返回的是Session的LANGUAGE和 TERRITORY数据库的字符集。
参考： http://www.oracle.com/technology/tech/globalization/htdocs/nls_lang%20faq.htm
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The NLS_LANG environment variable has three components:language, territory, and charset.
NLS_LANG is defined for each session by means of an environment variable or equivalent platform-specific mechanism. Different sessions connected to the same database can specify different values for NLS_LANG.
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