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> Use this file to discover all available pages before exploring further.

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# prefect-sqlalchemy

# Welcome!

`prefect-sqlalchemy` helps you connect to a database in your Prefect flows.

## Getting started

### Install `prefect-sqlalchemy`

The following command will install a version of `prefect-sqlalchemy` compatible with your installed version of `prefect`.
If you don't already have `prefect` installed, it will install the newest version of `prefect` as well.

```bash  theme={null}
pip install "prefect[sqlalchemy]"
```

Upgrade to the latest versions of `prefect` and `prefect-sqlalchemy`:

```bash  theme={null}
pip install -U "prefect[sqlalchemy]"
```

### Register newly installed block types

Register the block types in the `prefect-sqlalchemy` module to make them available for use.

```bash  theme={null}
prefect block register -m prefect_sqlalchemy
```

## Examples

### Save credentials to a block

To use the `load` method on Blocks, you must have a block saved through code or saved through the UI.

```python  theme={null}
from prefect_sqlalchemy import SqlAlchemyConnector, ConnectionComponents, SyncDriver

connector = SqlAlchemyConnector(
    connection_info=ConnectionComponents(
        driver=SyncDriver.POSTGRESQL_PSYCOPG2,
        username="USERNAME-PLACEHOLDER",
        password="PASSWORD-PLACEHOLDER",
        host="localhost",
        port=5432,
        database="DATABASE-PLACEHOLDER",
    )
)

connector.save("BLOCK_NAME-PLACEHOLDER")
```

Load the saved block that holds your credentials:

```python  theme={null}
from prefect_sqlalchemy import SqlAlchemyConnector

SqlAlchemyConnector.load("BLOCK_NAME-PLACEHOLDER")
```

The required arguments depend upon the desired driver. For example, SQLite requires only the `driver` and `database` arguments:

```python  theme={null}
from prefect_sqlalchemy import SqlAlchemyConnector, ConnectionComponents, SyncDriver

connector = SqlAlchemyConnector(
    connection_info=ConnectionComponents(
        driver=SyncDriver.SQLITE_PYSQLITE,
        database="DATABASE-PLACEHOLDER.db"
    )
)

connector.save("BLOCK_NAME-PLACEHOLDER")
```

### Work with databases in a flow

To set up a table, use the `execute` and `execute_many` methods.

Use the `fetch_many` method to retrieve data in a stream until there's no more data.

Use the `SqlAlchemyConnector` as a context manager, to ensure that the SQLAlchemy engine and any connected resources are closed properly after you're done with them.

<Note>
  **Async support**

  For async workflows with async database drivers (like `AsyncDriver.SQLITE_AIOSQLITE` or `AsyncDriver.POSTGRESQL_ASYNCPG`), use `AsyncSqlAlchemyConnector` instead of `SqlAlchemyConnector`. See the **Async** tab below for a complete example.
</Note>

<Tabs>
  <Tab title="Sync">
    ```python  theme={null}
    from prefect import flow, task
    from prefect_sqlalchemy import SqlAlchemyConnector


    @task
    def setup_table(block_name: str) -> None:
        with SqlAlchemyConnector.load(block_name) as connector:
            connector.execute(
                "CREATE TABLE IF NOT EXISTS customers (name varchar, address varchar);"
            )
            connector.execute(
                "INSERT INTO customers (name, address) VALUES (:name, :address);",
                parameters={"name": "Marvin", "address": "Highway 42"},
            )
            connector.execute_many(
                "INSERT INTO customers (name, address) VALUES (:name, :address);",
                seq_of_parameters=[
                    {"name": "Ford", "address": "Highway 42"},
                    {"name": "Unknown", "address": "Highway 42"},
                ],
            )

    @task
    def fetch_data(block_name: str) -> list:
        all_rows = []
        with SqlAlchemyConnector.load(block_name) as connector:
            while True:
                # Repeated fetch* calls using the same operation will
                # skip re-executing and instead return the next set of results
                new_rows = connector.fetch_many("SELECT * FROM customers", size=2)
                if len(new_rows) == 0:
                    break
                all_rows.append(new_rows)
        return all_rows

    @flow
    def sqlalchemy_flow(block_name: str) -> list:
        setup_table(block_name)
        all_rows = fetch_data(block_name)
        return all_rows


    if __name__ == "__main__":
        sqlalchemy_flow("BLOCK-NAME-PLACEHOLDER")
    ```
  </Tab>

  <Tab title="Async">
    ```python  theme={null}
    from prefect import flow, task
    from prefect_sqlalchemy import AsyncSqlAlchemyConnector
    import asyncio


    @task
    async def setup_table(block_name: str) -> None:
        async with await AsyncSqlAlchemyConnector.load(block_name) as connector:
            await connector.execute(
                "CREATE TABLE IF NOT EXISTS customers (name varchar, address varchar);"
            )
            await connector.execute(
                "INSERT INTO customers (name, address) VALUES (:name, :address);",
                parameters={"name": "Marvin", "address": "Highway 42"},
            )
            await connector.execute_many(
                "INSERT INTO customers (name, address) VALUES (:name, :address);",
                seq_of_parameters=[
                    {"name": "Ford", "address": "Highway 42"},
                    {"name": "Unknown", "address": "Highway 42"},
                ],
            )

    @task
    async def fetch_data(block_name: str) -> list:
        all_rows = []
        async with await AsyncSqlAlchemyConnector.load(block_name) as connector:
            while True:
                # Repeated fetch* calls using the same operation will
                # skip re-executing and instead return the next set of results
                new_rows = await connector.fetch_many("SELECT * FROM customers", size=2)
                if len(new_rows) == 0:
                    break
                all_rows.append(new_rows)
        return all_rows

    @flow
    async def sqlalchemy_flow(block_name: str) -> list:
        await setup_table(block_name)
        all_rows = await fetch_data(block_name)
        return all_rows


    if __name__ == "__main__":
        asyncio.run(sqlalchemy_flow("BLOCK-NAME-PLACEHOLDER"))
    ```
  </Tab>
</Tabs>

## Resources

Refer to the `prefect-sqlalchemy` [SDK documentation](/integrations/prefect-sqlalchemy/api-ref/prefect_sqlalchemy-credentials) to explore all the capabilities of the `prefect-sqlalchemy` library.

For assistance using SQLAlchemy, consult the [SQLAlchemy documentation](https://www.sqlalchemy.org/).


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