Django（1.5）对我来说很好用，但是当我启动Python解释器（Python 3）进行检查时，尝试导入时会遇到最奇怪的错误from django.contrib.auth.models import User--

Traceback (most recent call last):
  File "/usr/local/lib/python3.2/dist-packages/django/conf/__init__.py", line 36, in _setup
    settings_module = os.environ[ENVIRONMENT_VARIABLE]
  File "/usr/lib/python3.2/os.py", line 450, in __getitem__
    value = self._data[self.encodekey(key)]
KeyError: b'DJANGO_SETTINGS_MODULE'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/local/lib/python3.2/dist-packages/django/contrib/auth/models.py", line 8, in <module>
    from django.db import models
  File "/usr/local/lib/python3.2/dist-packages/django/db/__init__.py", line 11, in <module>
    if settings.DATABASES and DEFAULT_DB_ALIAS not in settings.DATABASES:
  File "/usr/local/lib/python3.2/dist-packages/django/conf/__init__.py", line 52, in __getattr__
    self._setup(name)
  File "/usr/local/lib/python3.2/dist-packages/django/conf/__init__.py", line 45, in _setup
    % (desc, ENVIRONMENT_VARIABLE))

django.core.exceptions.ImproperlyConfigured: Requested setting DATABASES, 
  but settings are not configured. You must either define the environment 
  variable DJANGO_SETTINGS_MODULE or call settings.configure() 
  before accessing settings.

当它在Python解释器之外可以正常工作时，如何对其进行不正确的配置？在我的Django设置中，DATABASES设置为：

DATABASES = {
    'default': {
        'ENGINE': 'django.db.backends.postgresql_psycopg2', # Add 'postgresql_psycopg2', 'mysql', 'sqlite3' or 'oracle'.
        'NAME': 'django_db', # Or path to database file if using sqlite3.
        # The following settings are not used with sqlite3:
        'USER': 'zamphatta',
        'PASSWORD': 'mypassword91',
        'HOST': '', # Empty for localhost through domain sockets or '127.0.0.1' for localhost through TCP.
        'PORT': '', # Set to empty string for default.
    }
}

…这是如何配置不正确的？