# SQL (Relational) Databases { #sql-relational-databases }

**FastAPI** doesn't require you to use a SQL (relational) database. But you can use **any database** that you want.

Here we'll see an example using <a href="https://sqlmodel.tiangolo.com/" class="external-link" target="_blank">SQLModel</a>.

<div class="screenshot">
<img src="/img/tutorial/sql-databases/image01.png">
</div>

## Atualizar o App com Múltiplos Modelos

Agora vamos **refatorar** este app um pouco para aumentar a **segurança** e **versatilidade**.

```

</div>

그런 다음 `/docs` UI로 이동하면, **FastAPI**가 해당 **model들**을 사용하여 API **문서를 생성**하는 것으르 확인할 수 있습니다. 또한 이 모델들은 데이터를 직렬화하고 검증하는 데에도 사용됩니다.

<div class="screenshot">
<img src="/img/tutorial/sql-databases/image01.png">
</div>

## 여러 모델로 애플리케이션 업데이트

이제 애플리케이션을 약간 **리팩토링**하여 **보안**과 **유연성**을 개선해 보겠습니다.

이전 애플리케이션의 UI를 보면, 지금까지는 클라이언트가 생성할 `Hero`의 `id`를 직접 지정할 수 있다는 것을 알 수 있습니다. 😱

<div class="screenshot">
<img src="/img/tutorial/sql-databases/image01.png">
</div>

## Добавление в приложение дополнительных (вспомогательных) моделей

Теперь давайте проведём **рефакторинг** нашего приложения, чтобы сделать его более безопасным и более универсальным.

<div class="screenshot">
<img src="/img/tutorial/sql-databases/image01.png">
</div>

## Actualizar la App con Múltiples Modelos

Ahora vamos a **refactorizar** un poco esta aplicación para aumentar la **seguridad** y la **versatilidad**.

# Testing a Database { #testing-a-database }

You can study about databases, SQL, and SQLModel in the <a href="https://sqlmodel.tiangolo.com/" class="external-link" target="_blank">SQLModel docs</a>. 🤓

There's a mini <a href="https://sqlmodel.tiangolo.com/tutorial/fastapi/" class="external-link" target="_blank">tutorial on using SQLModel with FastAPI</a>. ✨

Dit betekent ook dat je in veel gevallen het object dat je van een request krijgt **direct naar je database** kunt sturen, omdat alles automatisch wordt gevalideerd.

Hetzelfde geldt ook andersom, in veel gevallen kun je dus het object dat je krijgt van de database **direct doorgeven aan de client**.

This also means that in many cases you can pass the same object you get from a request **directly to the database**, as everything is validated automatically.

The same applies the other way around, in many cases you can just pass the object you get from the database **directly to the client**.

# Test Guide

```bash
cd tests
# prepare test databases
docker-compose up

# run all tests
./tests_all.sh

You will see examples of this in the next chapters, about relational and NoSQL databases, security, etc.

## **FastAPI** compatibility { #fastapi-compatibility }

The simplicity of the dependency injection system makes **FastAPI** compatible with:

* all the relational databases
* NoSQL databases
* external packages
* external APIs
* authentication and authorization systems