old_contents: import os
  
  from .base import BASE_DIR
  
  # Database
  # https://docs.djangoproject.com/en/1.9/ref/settings/#databases
  
  DATABASES = {
      'default': {
          'ENGINE': 'django.db.backends.sqlite3',
          'NAME': os.path.join(BASE_DIR, 'db.sqlite3'),
      }
  }
  
new_contents: # dj_datbase_url
  # https://github.com/kennethreitz/dj-database-url
  
  import dj_database_url
  import os
  
  
  DATABASES = {}
  DATABASES['default'] = dj_database_url.config(
      default=os.environ.get("DATABASE_URL")
  )
  
subject: update database setting: using dj_database_url