Oracle/NLS

Get current NLS status:

SELECT * FROM NLS_SESSION_PARAMETERS;
SELECT * FROM NLS_INSTANCE_PARAMETERS;
SELECT * FROM NLS_DATABASE_PARAMETERS;

Change current NLS territory for current session:

-- check current state
SELECT * FROM NLS_SESSION_PARAMETERS WHERE PARAMETER = 'NLS_TERRITORY';
-- change to 'AMERICA'
ALTER SESSION SET NLS_TERRITORY = 'AMERICA';

Those changes will affect procedures etc., e.g. when extracting day in week from a date.