我是Python Django的初学者。我的Django项目运行正常。但是我不知道何时运行命令
django-admin runserver
我遇到错误，请帮我一下突然发生了什么。它发生在所有Django项目中。该如何解决？
django.core.exceptions.ImproperlyConfigured: Requested setting DEBUG, but settings are not configured. You must either define the environment variable DJANGO_SETTINGS_MODULE or call settings.configure() before accessing settings.