{!../../../docs_src/async_sql_databases/tutorial001.py!}
```

!!! tip
    Notice that all this code is pure SQLAlchemy Core.

    `databases` is not doing anything here yet.

## Import and set up `databases`

* Import `databases`.
* Create a `DATABASE_URL`.
* Create a `database` object.

```Python hl_lines="3  9  12"
{!../../../docs_src/async_sql_databases/tutorial001.py!}
```

!!! tip

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,

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()

`sql_app` 🔜 ✔️ 📄 📁:

* `sql_app/__init__.py`: 🛁 📁.

* `sql_app/database.py`:

```Python
{!../../../docs_src/sql_databases_peewee/sql_app/database.py!}
```

* `sql_app/models.py`:

```Python
{!../../../docs_src/sql_databases_peewee/sql_app/models.py!}
```

* `sql_app/schemas.py`:

```Python
{!../../../docs_src/sql_databases_peewee/sql_app/schemas.py!}
```

* `sql_app/crud.py`:

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

* ✍ `DATABASE_URL`.
* ✍ `database` 🎚.

```Python hl_lines="3  9  12"
{!../../../docs_src/async_sql_databases/tutorial001.py!}
```

!!! tip
    🚥 👆 🔗 🎏 💽 (✅ ✳), 👆 🔜 💪 🔀 `DATABASE_URL`.

## ✍ 🏓

👉 💼, 👥 🏗 🏓 🎏 🐍 📁, ✋️ 🏭, 👆 🔜 🎲 💚 ✍ 👫 ⏮️ ⚗, 🛠️ ⏮️ 🛠️, ♒️.

📥, 👉 📄 🔜 🏃 🔗, ▶️️ ⏭ ▶️ 👆 **FastAPI** 🈸.

* ✍ `engine`.
* ✍ 🌐 🏓 ⚪️➡️ `metadata` 🎚.

```Python hl_lines="25-28"

* 创建 `DATABASE_URL`
* 创建 `database`

```Python hl_lines="3  9  12"
{!../../../docs_src/async_sql_databases/tutorial001.py!}
```

!!! tip "提示"

    连接 PostgreSQL 等数据库时，需要修改 `DATABASE_URL`。

## 创建表

本例中，使用 Python 文件创建表，但在生产环境中，应使用集成迁移等功能的 Alembic 创建表。

本例在启动 **FastAPI** 应用前，直接执行这些操作。

* 创建 `engine`
* 使用 `metadata` 对象创建所有表

```Python hl_lines="25-28"

initial_fake_database = {"rick": "Rick Sanchez"}

fake_database = initial_fake_database.copy()

initial_state = {"except": False, "finally": False}

state = initial_state.copy()

app = FastAPI()


async def get_database():
    temp_database = fake_database.copy()
    try:
        yield temp_database
        fake_database.update(temp_database)
    except HTTPException:

---> 100%
```

</div>

## 创建 SQLAlchemy 部件

让我们转到文件`sql_app/database.py`。

### 导入 SQLAlchemy 部件

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

### 为 SQLAlchemy 定义数据库 URL地址

```Python hl_lines="5-6"
{!../../../docs_src/sql_databases/sql_app/database.py!}
```

在这个例子中，我们正在“连接”到一个 SQLite 数据库（用 SQLite 数据库打开一个文件）。

from fastapi.testclient import TestClient
from sqlalchemy import create_engine
from sqlalchemy.orm import sessionmaker

from ..database import Base
from ..main import app, get_db

SQLALCHEMY_DATABASE_URL = "sqlite:///./test.db"

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