First you need to install `SQLAlchemy`:

<div class="termy">

```console
$ pip install sqlalchemy

---> 100%
```

</div>

## Create the SQLAlchemy parts

Let's refer to the file `sql_app/database.py`.

### Import the SQLAlchemy parts

```Python hl_lines="1-3"
{!../../../docs_src/sql_databases/sql_app/database.py!}
```

### Create a database URL for SQLAlchemy

```Python hl_lines="5-6"

Python 3.8+

FastAPI stands on the shoulders of giants:

* <a href="https://www.starlette.io/" class="external-link" target="_blank">Starlette</a> for the web parts.
* <a href="https://docs.pydantic.dev/" class="external-link" target="_blank">Pydantic</a> for the data parts.

## Installation

<div class="termy">

```console
$ pip install fastapi

---> 100%
```

</div>

It is designed to have functions that receive two parameters, one "request" and one "response". Then you "read" parts from the request, and "write" parts to the response. Because of this design, it is not possible to declare request parameters and bodies with standard Python type hints as function parameters.

    """
    Generate and return the HTML  that loads Swagger UI for the interactive
    API docs (normally served at `/docs`).

    You would only call this function yourself if you needed to override some parts,
    for example the URLs to use to load Swagger UI's JavaScript and CSS.

    Read more about it in the
    [FastAPI docs for Configure Swagger UI](https://fastapi.tiangolo.com/how-to/configure-swagger-ui/)

## Execution of dependencies with `yield`

The sequence of execution is more or less like this diagram. Time flows from top to bottom. And each column is one of the parts interacting or executing code.

```mermaid
sequenceDiagram

participant client as Client
participant handler as Exception handler
participant dep as Dep with yield
participant operation as Path Operation

## Returning a custom `Response`

The example above shows all the parts you need, but it's not very useful yet, as you could have just returned the `item` directly, and **FastAPI** would put it in a `JSONResponse` for you, converting it to a `dict`, etc. All that by default.

# Reference - Code API

Here's the reference or code API, the classes, functions, parameters, attributes, and
all the FastAPI parts you can use in your applications.

If you want to **learn FastAPI** you are much better off reading the

    - 💾 [PostgreSQL](https://www.postgresql.org) as the SQL database.
- 🚀 [React](https://react.dev) for the frontend.
    - 💃 Using TypeScript, hooks, Vite, and other parts of a modern frontend stack.
    - 🎨 [Chakra UI](https://chakra-ui.com) for the frontend components.
    - 🤖 An automatically generated frontend client.
    - 🦇 Dark mode support.

    ├── database.py
    ├── main.py
    └── schemas.py
```

This is almost the same structure as we had for the SQLAlchemy tutorial.

Now let's see what each file/module does.

## Create the Peewee parts

Let's refer to the file `sql_app/database.py`.

### The standard Peewee code

Let's first check all the normal Peewee code, create a Peewee database:

```Python hl_lines="3  5  22"

JSON Schema didn't have `examples`, so OpenAPI added it's own `example` field to its own modified version.

OpenAPI also added `example` and `examples` fields to other parts of the specification:

* <a href="https://github.com/OAI/OpenAPI-Specification/blob/main/versions/3.1.0.md#parameter-object" class="external-link" target="_blank">`Parameter Object` (in the specification)</a> that was used by FastAPI's: