Tests using `live_server` flush all data of my database

In order to access existing database, I put these code into conftest.py according to https://pytest-django.readthedocs.io/en/latest/database.html?highlight=rollback#using-an-existing-external-database-for-tests

@pytest.fixture(scope='session')
def django_db_setup():
    settings.DATABASES['default'] = {
        'ENGINE': 'django.db.backends.mysql',
        'HOST': 'db.example.com',
        'NAME': 'external_db',
    }

After running test functions like this one, all data of the database were flushed.

def test_xxx(live_server):
    r = requests.get(live_server + reverse("xxx"))
   # some assertions

Is there anyway to use live_server fixture without modifying the existing database?

Read the database setup guidance linked in the issue, then inspect conftest.py’s django_db_setup and the live_server fixture usage. Reproduce the test against the external MySQL database and verify that using live_server no longer flushes existing data.