python - 当我的目的只是读取现有的 Oracle 数据库时，为什么 django 尝试创建迁移表

Question

我的目的是连接到 Oracle 数据库并运行查询，以便在网页上填充这些结果。但是当我尝试运行 python manage.py migrate 时，出现以下错误。即使我使用选项 --fake-initial 或 --fake 也会出现同样的错误。我不想创建任何表。我刚刚在 settings.py 文件中进行了更改以连接到 oracle 数据库而不是 sqlite。

    Operations to perform:
  Apply all migrations: admin, auth, contenttypes, sessions
Running migrations:
Traceback (most recent call last):
  File "C:\Users\rishbans\Anaconda3\envs\DjangoProject\lib\site-packages\django\db\backends\utils.py", line 83, in _execute
    return self.cursor.execute(sql)
  File "C:\Users\rishbans\Anaconda3\envs\DjangoProject\lib\site-packages\django\db\backends\oracle\base.py", line 506, in execute
    return self.cursor.execute(query, self._param_generator(params))
cx_Oracle.DatabaseError: ORA-01031: insufficient privileges

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "C:\Users\rishbans\Anaconda3\envs\DjangoProject\lib\site-packages\django\db\migrations\recorder.py", line 55, in ensure_schema
    editor.create_model(self.Migration)
  File "C:\Users\rishbans\Anaconda3\envs\DjangoProject\lib\site-packages\django\db\backends\base\schema.py", line 312, in create_model
    self.execute(sql, params or None)
  File "C:\Users\rishbans\Anaconda3\envs\DjangoProject\lib\site-packages\django\db\backends\base\schema.py", line 133, in execute
    cursor.execute(sql, params)
  File "C:\Users\rishbans\Anaconda3\envs\DjangoProject\lib\site-packages\django\db\backends\utils.py", line 100, in execute
    return super().execute(sql, params)
  File "C:\Users\rishbans\Anaconda3\envs\DjangoProject\lib\site-packages\django\db\backends\utils.py", line 68, in execute
    return self._execute_with_wrappers(sql, params, many=False, executor=self._execute)
  File "C:\Users\rishbans\Anaconda3\envs\DjangoProject\lib\site-packages\django\db\backends\utils.py", line 77, in _execute_with_wrappers
    return executor(sql, params, many, context)
  File "C:\Users\rishbans\Anaconda3\envs\DjangoProject\lib\site-packages\django\db\backends\utils.py", line 85, in _execute
    return self.cursor.execute(sql, params)
  File "C:\Users\rishbans\Anaconda3\envs\DjangoProject\lib\site-packages\django\db\utils.py", line 89, in __exit__
    raise dj_exc_value.with_traceback(traceback) from exc_value
  File "C:\Users\rishbans\Anaconda3\envs\DjangoProject\lib\site-packages\django\db\backends\utils.py", line 83, in _execute
    return self.cursor.execute(sql)
  File "C:\Users\rishbans\Anaconda3\envs\DjangoProject\lib\site-packages\django\db\backends\oracle\base.py", line 506, in execute
    return self.cursor.execute(query, self._param_generator(params))
django.db.utils.DatabaseError: ORA-01031: insufficient privileges

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "manage.py", line 15, in <module>
    execute_from_command_line(sys.argv)
  File "C:\Users\rishbans\Anaconda3\envs\DjangoProject\lib\site-packages\django\core\management\__init__.py", line 381, in execute_from_command_line
    utility.execute()
  File "C:\Users\rishbans\Anaconda3\envs\DjangoProject\lib\site-packages\django\core\management\__init__.py", line 375, in execute
    self.fetch_command(subcommand).run_from_argv(self.argv)
  File "C:\Users\rishbans\Anaconda3\envs\DjangoProject\lib\site-packages\django\core\management\base.py", line 316, in run_from_argv
    self.execute(*args, **cmd_options)
  File "C:\Users\rishbans\Anaconda3\envs\DjangoProject\lib\site-packages\django\core\management\base.py", line 353, in execute
    output = self.handle(*args, **options)
  File "C:\Users\rishbans\Anaconda3\envs\DjangoProject\lib\site-packages\django\core\management\base.py", line 83, in wrapped
    res = handle_func(*args, **kwargs)
  File "C:\Users\rishbans\Anaconda3\envs\DjangoProject\lib\site-packages\django\core\management\commands\migrate.py", line 203, in handle
    fake_initial=fake_initial,
  File "C:\Users\rishbans\Anaconda3\envs\DjangoProject\lib\site-packages\django\db\migrations\executor.py", line 91, in migrate
    self.recorder.ensure_schema()
  File "C:\Users\rishbans\Anaconda3\envs\DjangoProject\lib\site-packages\django\db\migrations\recorder.py", line 57, in ensure_schema
    raise MigrationSchemaMissing("Unable to create the django_migrations table (%s)" % exc)
django.db.migrations.exceptions.MigrationSchemaMissing: Unable to create the django_migrations table (ORA-01031: insufficient privileges)

应用程序/models.py

from django.db import connection

# Create your models here.

def my_custom_sql(self):
    with connection.cursor() as cursor:
        cursor.execute("SELECT * FROM MY_TABLE")
        row = cursor.fetchone()

    return row

Answer 1

Django 需要一个读/写数据库作为其默认数据库来跟踪名为django_migrations的表中的迁移。更改您的设置以将 SQLite(或其他)数据库设置为您的默认数据库，然后为您的只读 Oracle 数据库创建一个名为 my_oracle 的第二个条目:

DATABASES = {
    'default': {
        'ENGINE': 'django.db.backends.sqlite3',
        'NAME': 'mydatabase',
    },
    'my_oracle': {
        'ENGINE': 'django.db.backends.oracle',
        'NAME': '',
        'USER': '',
        'PASSWORD': '',
        'HOST': '',
        'PORT': '',
    },
}

然后你可以:

from django.db import connections

def my_custom_sql(self):
    with connections["my_oracle"].cursor() as cursor:
        cursor.execute("SELECT * FROM MY_TABLE")
        row = cursor.fetchone()

        return row

祝你好运!