## Create the database

Because now we are going to use a new database in a new file, we need to make sure we create the database with:

```Python
Base.metadata.create_all(bind=engine)
```

That is normally called in `main.py`, but the line in `main.py` uses the database file `sql_app.db`, and we need to make sure we create `test.db` for the tests.

So we add that line here, with the new file.

## Server Machine and Server Program

There's a small detail about names to keep in mind. 💡

The word "**server**" is commonly used to refer to both the remote/cloud computer (the physical or virtual machine) and also the program that is running on that machine (e.g. Uvicorn).

Just keep in mind that when you read "server" in general, it could refer to one of those two things.

engine = create_engine(
    SQLALCHEMY_DATABASE_URL,
    connect_args={"check_same_thread": False},
    poolclass=StaticPool,
)
TestingSessionLocal = sessionmaker(autocommit=False, autoflush=False, bind=engine)


Base.metadata.create_all(bind=engine)


def override_get_db():
    try:
        db = TestingSessionLocal()
        yield db
    finally:
        db.close()

    * 📥 👥 🚶‍♀️ 🎓 👈 🐁 💪 🗄 & ⚙️ ⏮️:

        ```Python
        import uvicorn.workers.UvicornWorker
        ```

* `--bind`: 👉 💬 🐁 📢 & ⛴ 👂, ⚙️ ❤ (`:`) 🎏 📢 & ⛴.
    * 🚥 👆 🏃‍♂ Uvicorn 🔗, ↩️ `--bind 0.0.0.0:80` (🐁 🎛) 👆 🔜 ⚙️ `--host 0.0.0.0` & `--port 80`.

🔢, 👆 💪 👀 👈 ⚫️ 🎦 **🕹** (🛠️ 🆔) 🔠 🛠️ (⚫️ 🔢).

👆 💪 👀 👈:

     * 这里我们传递了 Gunicorn 可以导入和使用的类：

         ```Python
         import uvicorn.workers.UvicornWorker
         ```

* `--bind`：这告诉 Gunicorn 要监听的 IP 和端口，使用冒号 (`:`) 分隔 IP 和端口。
     * 如果您直接运行 Uvicorn，则可以使用`--host 0.0.0.0`和`--port 80`，而不是`--bind 0.0.0.0:80`（Gunicorn 选项）。


在输出中，您可以看到它显示了每个进程的 **PID**（进程 ID）（它只是一个数字）。

你可以看到：

* Gunicorn **进程管理器** 以 PID `19499` 开头（在您的情况下，它将是一个不同的数字）。

        ```Python
        import uvicorn.workers.UvicornWorker
        ```

* `--bind`: This tells Gunicorn the IP and the port to listen to, using a colon (`:`) to separate the IP and the port.
    * If you were running Uvicorn directly, instead of `--bind 0.0.0.0:80` (the Gunicorn option) you would use `--host 0.0.0.0` and `--port 80`.

    ```

    </div>

=== "Hypercorn"

    <div class="termy">

    ```console
    $ hypercorn main:app --bind 0.0.0.0:80

    Running on 0.0.0.0:8080 over http (CTRL + C to quit)
    ```

    </div>

!!! warning "Achtung"
    Denken Sie daran, die Option `--reload` zu entfernen, wenn Sie diese verwendet haben.

Just use any kind of model, any kind of class, any kind of database that you need for your application. **FastAPI** has you covered with the dependency injection system.

## Code size

This example might seem verbose. Keep in mind that we are mixing security, data models, utility functions and *path operations* in the same file.

!!! tip "提示"

    为减少代码重复，最好把这段代码写成函数，在 `database.py` 与 `tests/test_sql_app.py`中使用。

    为了把注意力集中在测试代码上，本例只是复制了这段代码。

## 创建数据库

因为现在是想在新文件中使用新数据库，所以要使用以下代码创建数据库：

```Python
Base.metadata.create_all(bind=engine)
```

一般是在 `main.py` 中调用这行代码，但在 `main.py` 里，这行代码用于创建 `sql_app.db`，但是现在要为测试创建 `test.db`。

因此，要在测试代码中添加这行代码创建新的数据库文件。

```Python hl_lines="16"
{!../../../docs_src/sql_databases/sql_app/tests/test_sql_app.py!}

Several of these are explored in the next chapters of the tutorial.

## Order matters

When creating *path operations*, you can find situations where you have a fixed path.

Like `/users/me`, let's say that it's to get data about the current user.

And then you can also have a path `/users/{user_id}` to get data about a specific user by some user ID.