!!! tip
    You could adopt ideas from the section about SQLAlchemy ORM ([SQL (Relational) Databases](../tutorial/sql-databases.md){.internal-link target=_blank}), like using utility functions to perform operations in the database, independent of your **FastAPI** code.

from typing import List

import databases
import sqlalchemy
from fastapi import FastAPI
from pydantic import BaseModel

# SQLAlchemy specific code, as with any other app
DATABASE_URL = "sqlite:///./test.db"
# DATABASE_URL = "postgresql://user:password@postgresserver/db"

database = databases.Database(DATABASE_URL)

metadata = sqlalchemy.MetaData()

notes = sqlalchemy.Table(
    "notes",
    metadata,

#### 🏒 🗳

🚥 👆 ⚙️ <a href="https://docs.peewee-orm.com/en/latest/peewee/database.html#dynamically-defining-a-database" class="external-link" target="_blank">🏒 🗳</a>, ☑ 💽 `db.obj`.

, 👆 🔜 ⏲ ⚫️ ⏮️:

```Python hl_lines="3-4"
async def reset_db_state():
    database.db.obj._state._state.set(db_state_default.copy())
    database.db.obj._state.reset()
```

### ✍ 👆 **FastAPI** *➡ 🛠️*

  about every particular db's extension or quirk.

* Separate out the basic implementation of a database driver
  (implementing the sql/driver interfaces) vs the implementation
  of all the user-level types and convenience methods.
  In a nutshell:

  User Code ---> sql package (concrete types) ---> sql/driver (interfaces)
  Database Driver -> sql (to register) + sql/driver (implement interfaces)

pkg database/sql, const LevelDefault = 0
pkg database/sql, const LevelDefault IsolationLevel
pkg database/sql, const LevelLinearizable = 7
pkg database/sql, const LevelLinearizable IsolationLevel
pkg database/sql, const LevelReadCommitted = 2
pkg database/sql, const LevelReadCommitted IsolationLevel
pkg database/sql, const LevelReadUncommitted = 1
pkg database/sql, const LevelReadUncommitted IsolationLevel

from fastapi import Depends, FastAPI, HTTPException

from . import crud, database, models, schemas
from .database import db_state_default

database.db.connect()
database.db.create_tables([models.User, models.Item])
database.db.close()

app = FastAPI()

sleep_time = 10


async def reset_db_state():
    database.db._state._state.set(db_state_default.copy())
    database.db._state.reset()

		return
	}

	// Try proxies in turn until we find out how to connect to this database.
	//
	// Before accessing any checksum database URL using a proxy, the proxy
	// client should first fetch <proxyURL>/sumdb/<sumdb-name>/supported.
	//
	// If that request returns a successful (HTTP 200) response, then the proxy
	// supports proxying checksum database requests. In that case, the client

// Pinger is an optional interface that may be implemented by a [Conn].
//
// If a [Conn] does not implement Pinger, the [database/sql.DB.Ping] and
// [database/sql.DB.PingContext] will check if there is at least one [Conn] available.
//
// If Conn.Ping returns [ErrBadConn], [database/sql.DB.Ping] and [database/sql.DB.PingContext] will remove
// the [Conn] from pool.
type Pinger interface {
	Ping(ctx context.Context) error
}

import peewee

from .database import db


class User(peewee.Model):
    email = peewee.CharField(unique=True, index=True)
    hashed_password = peewee.CharField()
    is_active = peewee.BooleanField(default=True)

    class Meta:
        database = db


class Item(peewee.Model):
    title = peewee.CharField(index=True)
    description = peewee.CharField(index=True)
    owner = peewee.ForeignKeyField(User, backref="items")

// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package sql_test

import (
	"context"
	"database/sql"
	"flag"
	"log"
	"os"
	"os/signal"
	"time"
)

var pool *sql.DB // Database connection pool.

func Example_openDBCLI() {
	id := flag.Int64("id", 0, "person ID to find")
	dsn := flag.String("dsn", os.Getenv("DSN"), "connection data source name")