Setting NLS parameters in Oracle at the database, instance and session level

NLS parameters can be set at the database, instance and session level.

Settings (of a parameter) of the session levels are stronger than those of the database and instance level, that is, they override those. Similarly, instance settings are stronger than those of the database level.

The database level settings are set through the values in the init.ora at the creation of the database.

Instance level settings are those that are in effect in the init.ora (or spfile) when the instance was started.

Session level setting are changed through a

alter session set <a href='http://www.adp-gmbh.ch/ora/admin/init_params/nls.html'>&lt;nls-parameter&gt;</a>. 

See also globalization in Oracle, nls_database_parameters, nls_instance_parameters and nls_session_parameters.