Checking the value of NLS_LANG in SQL*Plus on Windows

Oracle Support Note *179113.1* offers a, ahem, clever way to display the used value for NLS_LANG on Windows in SQL*Plus.

First, it can be verified if the environment variable NLS_LANG is set:

SQL> host echo %NLS_LANG%

SQL*Plus will answer with either something similar to

AMERICAN_AMERICA.WE8MSWIN1252

or with

%NLS_LANG%

In the first case, the environment variable is set and its value, as displayed by the echo command is the value for NLS_LANG.

If the variable is not set, that is in the second case, the following trick allows to determine its value none the less:

SQL> @.[%NLS_LANG%].

There are again two possibilities how SQL*Plus will react. Either

SP2-0310: unable to open file ".[AMERICAN_AMERICA.WE8ISO8859P1]..sql"

or

SP2-0310: unable to open file ".[%NLS_LANG%]."

In the first case, the value for NLS_LANG is set in the Windows registry (to the value between [ and ]). In the second case, NLS_LANG is not even set in the Windows registry.

Incidentally, this seems to be achieved much easier like so

SQL> select sys_context('userenv', 'language') from dual;