16 copyright © 2006, oracle. all rights reserved. using globalization support

16Copyright © 2006, Oracle. All rights reserved.

Using Globalization Support

16-2 Copyright © 2006, Oracle. All rights reserved.

Objectives

After completing this lesson, you should be able to:

• Determine a correct database character set that meets your business requirements

• Obtain globalization support configuration information

• Customize language-dependent behavior for the database and individual sessions

• Specify different linguistic sorts for queries

• Retrieve data that matches a search string ignoring case or accent differences


What Every DBA Needs to Know

• What is a character set?

• How are character sets used?

• Problems to avoid

• Choosing your character set

• Obtaining character set information

• Specifying language-dependent behavior

• Using linguistic searching and sorting

• Using data conversion


What Is a Character Set?

The Oracle database supports different classes of character-encoding schemes:

• Single-byte character sets– 7-bit– 8-bit

• Multibyte character sets, including Unicode


Understanding Unicode

Supplementary characters

AL40UTF8 AL16UTF16

63

EE AA 9E

F0 9D 84 9E

64

C3

D0 A4

B6

á

t

d

ö

0063

00E1

0074

A89E

D834 DD1E

0064

00F6

0424

c

C3

74

91

Encoding: Representing characters with byte sequences


How Are Character Sets Used?

• Oracle Net compares the client NLS_LANG setting to the character set on the server.

• If needed, conversion occurs automatically and transparently.

Client

Oracle Net

NLS_LANG

Server


Example:

No conversion occurs, because it does not seem to be required.

Issue: Invalid data are entered into the database.

Problems to Avoid

ServerDatabase character set:

AL32URF8

Client

Windows English

Code page: WE8MSWIN1252

NLS_LANG:

AL32UTF8 Oracle Net


CREATE DATABASE ...CHARACTER SET US7ASCII NATIONAL CHARACTER SETUTF8 ...

% export NLS_LANG= SIMPLIFIED CHINESE_HONGKONG.US7ASCII

Another Sample Problem


Choosing Your Character Set

• Trade-offs to consider

• Choosing the correct character set that meets your business requirements now and in the future

• Specifying the character set

• Changing the character set after database creation


Database Character Sets and National Character Sets

Can store Unicode using either AL16UTF16 or UTF8

Can store varying-width character sets

Store data columns of type NCHAR, NVARCHAR2, NCLOB

Store data columns of type CHAR, VARCHAR2, CLOB, LONG

Can be exchangedCannot be changed without re-creation, few exceptions

Defined at creation timeDefined at creation time

National Character SetsDatabase Character Sets


Obtaining Character Set Information

SQL> SELECT parameter, value 2 FROM nls_database_parameters

3 WHERE parameter LIKE '%CHARACTERSET%';

PARAMETER VALUE----------------------- -------------NLS_CHARACTERSET WE8ISO8859P1NLS_NCHAR_CHARACTERSET AL16UTF16

2 rows selected.


SELECT sysdate FROM dual;

Initialization parameters for the database server

Environment variables for the clients

ALTER SESSION command

Specifying Language-Dependent Behavior

SQL function


Specifying Language-Dependent Behavior for the Session

• Specify the locale behavior with the NLS_LANG environment variable:– Language– Territory– Character set

• Set other NLS environment variables to:– Override database initialization parameter settings

for all sessions– Customize the locale behavior– Change the default location of the NLS library files

NLS_LANG=FRENCH_CANADA.WE8ISO8859P1


Language- and Territory-Dependent Parameters

Parameter

NLS_LANGUAGE NLS_DATE_LANGUAGE NLS_SORT

Default Values

AMERICAN AMERICAN BINARY

AMERICA $ $ AMERICA DD-MON-RR ., DD-MON-RRHH.MI.SSXFF AM DD-MON-RRHH.MI.SSXFF AM TZR

NLS_TERRITORY NLS_CURRENCY NLS_DUAL_CURRENCY NLS_ISO_CURRENCY NLS_DATE_FORMAT NLS_NUMERIC_CHARACTERS NLS_TIMESTAMP_FORMAT NLS_TIMESTAMP_TZ_FORMAT


ALTER SESSION SET NLS_DATE_FORMAT='DD.MM.YYYY';

DBMS_SESSION.SET_NLS('NLS_DATE_FORMAT','''DD.MM.YYYY''') ;

Specifying Language-Dependent Behavior

Using NLS parameters in SQL functions

SELECT TO_CHAR(hire_date,'DD.Mon.YYYY', 'NLS_DATE_LANGUAGE=FRENCH') FROM employeesWHERE hire_date > '01-JAN-2000';


Linguistic Searching and Sorting

Sort order can be affected by:

• Case sensitivity

• Diacritics or accent characters

• Combination of characters that is treated as a single character

• Phonetics or character appearance

• Cultural preferences


Linguistic Searching and Sorting

Three types of sorting:

• Binary sorting– Sorted according to the binary values of the

encoded characters

• Monolingual linguistic sorting– A two-pass sort based on a character’s assigned

major and minor values

• Multilingual linguistic sorting– Based on the ISO standard (ISO 14651), and the

Unicode 3.2 Standard for multilingual collation– Ordered by the number of strokes, PinYin, or

radicals for Chinese characters


Using Linguistic Searching and Sorting

You can specify the type of sort used for character data with the:

• NLS_SORT parameter– Default value derived from the NLS_LANG

environment variable, if set– Can be specified for the session, client, or server

• NLSSORT function – Defines the sorting method at the query

level


Case- and Accent-InsensitiveSearch and Sort

• Specify the linguistic name:

• Examples:

• Specify the sort action for WHERE clauses and PL/SQL blocks:

• Useful for migrated databases

NLS_SORT = <NLS_sort_name>[_AI | _CI]

NLS_SORT = FRENCH_M_AI

NLS_SORT = XGERMAN_CI

NLS_COMP = BINARY | ANSI


Support in SQL and Functions

• The following SQL clauses support NLS_SORT and NLS_COMP settings:– WHERE– ORDER BY– START WITH– HAVING– IN/NOT IN– BETWEEN– CASE-WHEN

• The NLSSORT() function supports the case-insensitive and accent-insensitive functionality.


Linguistic Index Support

• Create an index on linguistically sorted values.

• Rapidly query data without having to specify ORDER BY clause and NLSSORT:

• Set the NLS_SORT parameter to match the linguistic definition that you want to use for the linguistic sort when creating the index.

CREATE INDEX list_word ON list (NLSSORT(word, 'NLS_SORT=French_M'));

SELECT word FROM list;


Customizing Linguistic Searching and Sorting

You can customize linguistic sorting for:

• Ignorable characters

• Contracting or expanding characters

• Special combination letters or special letters

• Expanding characters or special letters

• Special uppercase and lowercase letters

• Context-sensitive characters

• Reverse secondary sorting

• Canonical equivalence


Implicit Conversion Between CLOB and NCLOB

Transparent implicit conversion is supported in:

• SQL IN and OUT bind variables for query and DML

• PL/SQL functions and procedure parameter passing

• PL/SQL variable assignment


NLS Data Conversion with Oracle Utilities

• Multiple data conversions can take place when data is exported from one database and imported into another if the same character sets are not used.

• External tables use the NLS settings on the server for determining the data character set.

• SQL*Loader:– Conventional path: Data is converted into the

session character set specified by NLS_LANG.– Direct path: Data is converted using client-side

directives.


NLS Data Conversion with Data Pump

• Data Pump Export always saves data in the same character set as the database from which the data originates.

• Data Pump Import converts the data to the character set of the target database, if needed.

• The Data Pump log file is written in the language specified by NLS_LANG for the session that started Data Pump.


Globalization Support Features

• Language support

• Territory support

• Character set support

• Linguistic sorting

• Message support

• Date and time formats

• Numeric formats

• Monetary formats

French

data

Japanese

data


Summary

In this lesson, you should have learned how to:

• Determine a correct database character set that meets your business requirements

• Obtain globalization support configuration information

• Customize language-dependent behavior for the database and individual sessions

• Specify different linguistic sorts for queries

• Retrieve data that matches a search string ignoring case or accent differences


Practice Overview: Using Globalization Support Features

This practice covers the following topics:

• Checking the database and national character set

• Identifying valid NLS values

• Setting NLS parameters

16 copyright © 2006, oracle. all rights reserved. using globalization support

Documents