NLS_LANG settings

To get the language setting of the current session :

SELECT USERENV ('language') FROM DUAL;

This returns the database character set, not the user’s though.

The NLS settings can be found in the following list, in this order. If a value is specified in NLS_SESSION_PARAMETERS, it has preference over a value in NLS_INSTANCE_PARAMETERS.

1. NLS_SESSION_PARAMETERS
2. NLS_INSTANCE_PARAMETERS
3. NLS_DATABASE_PARAMETERS