## CRUD utils

Now let's see the file `sql_app/crud.py`.

### Create all the CRUD utils

Create all the same CRUD utils as in the SQLAlchemy tutorial, all the code is very similar:

```Python hl_lines="1  4-5  8-9  12-13  16-20  23-24  27-30"
{!../../../docs_src/sql_databases_peewee/sql_app/crud.py!}
```

There are some differences with the code for the SQLAlchemy tutorial.

---

FastAPI is a modern, fast (high-performance), web framework for building APIs with Python based on standard Python type hints.

The key features are:

* **Fast**: Very high performance, on par with **NodeJS** and **Go** (thanks to Starlette and Pydantic). [One of the fastest Python frameworks available](#performance).
* **Fast to code**: Increase the speed to develop features by about 200% to 300%. *

Ensuite, vous pouvez servir cela avec le commandement `serve`:

<div class="termy">

```console
// Use the command "serve" after running "build-all"
$ python ./scripts/docs.py serve

Warning: this is a very simple server. For development, use mkdocs serve instead.
This is here only to preview a site with translations already built.
Make sure you run the build-all command first.
Serving at: http://127.0.0.1:8008
```

然后你可以使用命令 `serve` 来运行生成的站点：

<div class="termy">

```console
// Use the command "serve" after running "build-all"
$ python ./scripts/docs.py serve

Warning: this is a very simple server. For development, use mkdocs serve instead.
This is here only to preview a site with translations already built.
Make sure you run the build-all command first.
Serving at: http://127.0.0.1:8008
```

---

FastAPI is a modern, fast (high-performance), web framework for building APIs with Python based on standard Python type hints.

The key features are:

* **Fast**: Very high performance, on par with **NodeJS** and **Go** (thanks to Starlette and Pydantic). [One of the fastest Python frameworks available](#performance).
* **Fast to code**: Increase the speed to develop features by about 200% to 300%. *

    This is here only to preview a site with translations already built.

    Make sure you run the build-all command first.
    """
    typer.echo("Warning: this is a very simple server.")
    typer.echo("For development, use the command live instead.")
    typer.echo("This is here only to preview a site with translations already built.")

これは、コマンド`serve`で提供できます:

<div class="termy">

```console
// 「build-all」コマンドの実行の後に、「serve」コマンドを使います
$ python ./scripts/docs.py serve

Warning: this is a very simple server. For development, use mkdocs serve instead.
This is here only to preview a site with translations already built.
Make sure you run the build-all command first.
Serving at: http://127.0.0.1:8008
```

    They are more relevant for older versions, before OpenAPI 3.1.0 was available.

    You can consider this a brief OpenAPI and JSON Schema **history lesson**. 🤓

!!! warning
    These are very technical details about the standards **JSON Schema** and **OpenAPI**.

    If the ideas above already work for you, that might be enough, and you probably don't need these details, feel free to skip them.

<div class="termy">

```console
// Используйте команду "serve" после того, как отработает команда "build-all"
$ python ./scripts/docs.py serve

Warning: this is a very simple server. For development, use mkdocs serve instead.
This is here only to preview a site with translations already built.
Make sure you run the build-all command first.
Serving at: http://127.0.0.1:8008
```

    ```Python hl_lines="1  4"
    {!> ../../../docs_src/python_types/tutorial009b.py!}
    ```

#### Sử dụng `Union` hay `Optional`

If you are using a Python version below 3.10, here's a tip from my very **subjective** point of view:

Nếu bạn đang sử dụng phiên bản Python dưới 3.10, đây là một mẹo từ ý kiến rất "chủ quan" của tôi:

* 🚨 Tránh sử dụng `Optional[SomeType]`