Globalization can be specified at any or all of the following levels:

1 - The Database: Database Globalization is specified at the moment the database is created.

SELECT * FROM NLS_DATABASE_PARAMETERS;

2 - The Instance: The Instance Globalization configuration will exceed the Database Globalization configuration. For example, if you are using the RAC environment, which is more than Instances in the database, the Instance Globalization configuration will likely differ for each Instance. For example, users from America and Europe can access the database each through an Instance that is configured according to their different needs. The settings currently in effect in the Instance can be viewed through the NLS_INSTANCE_PARAMETERS View, which contains the same fields as the NLS_DATABASE_PARAMETERS except for three rows that do not apply to the Instance.

SELECT * FROM BLS_INSTANCE_PARAMETERS;

3 - The client environment: When the Oracle User Process starts working, it checks the environment in which it works to pick up the default Globalization. This mechanism means that it is possible for users who want to set different Globalizations to configure the Client to suit their needs, and then Oracle picks up these settings automatically without intervention from the database administrator or programmers. You can configure the Client by configuring the variable (NLS_LANG environment variable) This variable specifies both Set Character & Territory & Language.

To use French in Canada NLS_LANG= NLS_LANG=FRENCH_CANADA.WEISO8859P1 .

Regardless of Database and Instance Globalization, the user of this Client will display messages and format data according to the French Canadian language.

When the user sends data to the server, the user will enter this data in the Canadian French language, but the server stores this data according to the Database Globalization Setting.

The conversion process between Client-Site and Server-Site Globalization is done via Oracle Net, but it is possible that the process will not be completed successfully.

To convert the Client Globalization

C:\>set NLS_LANG= FRENCH_CANADA.WEISO8859P1

4 - The Session: The moment of connecting to the database. The user can use the ALTER SESSION command or the DBMS_SESSION package to configure the Globalization Session. This can usually be done programmatically and perhaps via a Logon Trigger.

Alter session set nls_date_format='dd.mm.yyyy';

Session Globalization configuration overrides Database and Instance and Client Globalization.

The current Globalization Settings in the Session can be viewed via V$NLS_INSTANCE View

5 - The statement: This level is the last level of Globalization and overrides all levels and is managed programmatically,

within each Statement where the NLS Parameter is used in the SQL Functions.