从命令行运行django数据库操作，报错：
django.core.exceptions.ImproperlyConfigured: Requested setting DEFAULT_INDEX_TABLESPACE, but settings are not configured. You must either define the environment variable DJANGO_SETTINGS_MODULE or call settings.configure() before accessing settings.
或
django.core.exceptions.ImproperlyConfigured: settings.DATABASES is improperly configured. Please supply the ENGINE value. Check settings documentation for more details.
看settings.py没有问题
解决的方法：
os.environ.setdefault("DJANGO_SETTINGS_MODULE", "mysite.settings")
注意这个是不行的：
from django.conf import settings
settings.configure()
两者都写也是不行的
