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Connect to TiDB with SQLAlchemy
Learn how to connect to TiDB using SQLAlchemy. This tutorial gives Python sample code snippets that work with TiDB using SQLAlchemy.
/tidb/dev/dev-guide-outdated-for-sqlalchemy

Connect to TiDB with SQLAlchemy

TiDB is a MySQL-compatible database, and SQLAlchemy is a popular Python SQL toolkit and Object Relational Mapper (ORM).

In this tutorial, you can learn how to use TiDB and SQLAlchemy to accomplish the following tasks:

  • Set up your environment.
  • Connect to your TiDB cluster using SQLAlchemy.
  • Build and run your application. Optionally, you can find sample code snippets for basic CRUD operations.

Note:

This tutorial works with TiDB Cloud Serverless, TiDB Cloud Dedicated, and TiDB Self-Managed clusters.

Prerequisites

To complete this tutorial, you need:

If you don't have a TiDB cluster, you can create one as follows:

If you don't have a TiDB cluster, you can create one as follows:

Run the sample app to connect to TiDB

This section demonstrates how to run the sample application code and connect to TiDB.

Step 1: Clone the sample app repository

Run the following commands in your terminal window to clone the sample code repository:

git clone https://github.com/tidb-samples/tidb-python-sqlalchemy-quickstart.git
cd tidb-python-sqlalchemy-quickstart

Step 2: Install dependencies

Run the following command to install the required packages (including SQLAlchemy and PyMySQL) for the sample app:

pip install -r requirements.txt

Why use PyMySQL?

SQLAlchemy is an ORM library that works with multiple databases. It provides a high-level abstraction of the database, which helps developers write SQL statements in a more object-oriented way. However, SQLAlchemy does not include a database driver. To connect to a database, you need to install a database driver. This sample application uses PyMySQL as the database driver, which is a pure Python MySQL client library that is compatible with TiDB and can be installed on all platforms.

You can also use other database drivers, such as mysqlclient and mysql-connector-python. But they are not pure Python libraries and require the corresponding C/C++ compiler and MySQL client for compiling. For more information, refer to SQLAlchemy official documentation.

Step 3: Configure connection information

Connect to your TiDB cluster depending on the TiDB deployment option you've selected.

Note:

Currently, TiDB Cloud Serverless clusters have a limitation: if there are no active connections for 5 minutes, they will shut down, which closes all connections. Therefore, when using SQLAlchemy with TiDB Cloud Serverless clusters, pooled connections might encounter OperationalError such as Lost connection to MySQL server during query or MySQL Connection not available. To avoid this error, you can set the pool_recycle parameter to 300. For more information, see Dealing with Disconnects in SQLAlchemy documentation.

  1. Navigate to the Clusters page, and then click the name of your target cluster to go to its overview page.

  2. Click Connect in the upper-right corner. A connection dialog is displayed.

  3. Ensure the configurations in the connection dialog match your operating environment.

    • Connection Type is set to Public
    • Branch is set to main
    • Connect With is set to General
    • Operating System matches your environment.

    Tip:

    If your program is running in Windows Subsystem for Linux (WSL), switch to the corresponding Linux distribution.

  4. Click Generate Password to create a random password.

    Tip:

    If you have created a password before, you can either use the original password or click Reset Password to generate a new one.

  5. Run the following command to copy .env.example and rename it to .env:

    cp .env.example .env

  6. Copy and paste the corresponding connection string into the .env file. The example result is as follows:

    TIDB_HOST='{host}'  # e.g. gateway01.ap-northeast-1.prod.aws.tidbcloud.com
TIDB_PORT='4000'
TIDB_USER='{user}'  # e.g. xxxxxx.root
TIDB_PASSWORD='{password}'
TIDB_DB_NAME='test'
CA_PATH='{ssl_ca}'  # e.g. /etc/ssl/certs/ca-certificates.crt (Debian / Ubuntu / Arch)

    Be sure to replace the placeholders {} with the connection parameters obtained from the connection dialog.

  7. Save the .env file.

  1. Navigate to the Clusters page, and then click the name of your target cluster to go to its overview page.

  2. Click Connect in the upper-right corner. A connection dialog is displayed.

  3. In the connection dialog, select Public from the Connection Type drop-down list, and then click CA cert to download the CA certificate.

    If you have not configured the IP access list, click Configure IP Access List or follow the steps in Configure an IP Access List to configure it before your first connection.

    In addition to the Public connection type, TiDB Dedicated supports Private Endpoint and VPC Peering connection types. For more information, see Connect to Your TiDB Dedicated Cluster.

  4. Run the following command to copy .env.example and rename it to .env:

    cp .env.example .env

  5. Copy and paste the corresponding connection string into the .env file. The example result is as follows:

    TIDB_HOST='{host}'  # e.g. tidb.xxxx.clusters.tidb-cloud.com
TIDB_PORT='4000'
TIDB_USER='{user}'  # e.g. root
TIDB_PASSWORD='{password}'
TIDB_DB_NAME='test'
CA_PATH='{your-downloaded-ca-path}'

    Be sure to replace the placeholders {} with the connection parameters obtained from the connection dialog, and configure CA_PATH with the certificate path downloaded in the previous step.

  6. Save the .env file.

  1. Run the following command to copy .env.example and rename it to .env:

    cp .env.example .env

  2. Copy and paste the corresponding connection string into the .env file. The example result is as follows:

    TIDB_HOST='{tidb_server_host}'
TIDB_PORT='4000'
TIDB_USER='root'
TIDB_PASSWORD='{password}'
TIDB_DB_NAME='test'

    Be sure to replace the placeholders {} with the connection parameters, and remove the CA_PATH line. If you are running TiDB locally, the default host address is 127.0.0.1, and the password is empty.

  3. Save the .env file.

Step 4: Run the code and check the result

  1. Execute the following command to run the sample code:

    python sqlalchemy_example.py

  2. Check the Expected-Output.txt to see if the output matches.

Sample code snippets

You can refer to the following sample code snippets to complete your own application development.

For complete sample code and how to run it, check out the tidb-samples/tidb-python-sqlalchemy-quickstart repository.

Connect to TiDB

from sqlalchemy import create_engine, URL
from sqlalchemy.orm import sessionmaker

def get_db_engine():
    connect_args = {}
    if ${ca_path}:
        connect_args = {
            "ssl_verify_cert": True,
            "ssl_verify_identity": True,
            "ssl_ca": ${ca_path},
        }
    return create_engine(
        URL.create(
            drivername="mysql+pymysql",
            username=${tidb_user},
            password=${tidb_password},
            host=${tidb_host},
            port=${tidb_port},
            database=${tidb_db_name},
        ),
        connect_args=connect_args,
    )

engine = get_db_engine()
Session = sessionmaker(bind=engine)

When using this function, you need to replace ${tidb_host}, ${tidb_port}, ${tidb_user}, ${tidb_password}, ${tidb_db_name} and ${ca_path} with the actual values of your TiDB cluster.

Define a table

from sqlalchemy import Column, Integer, String
from sqlalchemy.orm import declarative_base

Base = declarative_base()

class Player(Base):
    id = Column(Integer, primary_key=True)
    name = Column(String(32), unique=True)
    coins = Column(Integer)
    goods = Column(Integer)

    __tablename__ = "players"

For more information, refer to SQLAlchemy documentation: Mapping classes with declarative.

Insert data

with Session() as session:
    player = Player(name="test", coins=100, goods=100)
    session.add(player)
    session.commit()

For more information, refer to Insert data.

Query data

with Session() as session:
    player = session.query(Player).filter_by(name == "test").one()
    print(player)

For more information, refer to Query data.

Update data

with Session() as session:
    player = session.query(Player).filter_by(name == "test").one()
    player.coins = 200
    session.commit()

For more information, refer to Update data.

Delete data

with Session() as session:
    player = session.query(Player).filter_by(name == "test").one()
    session.delete(player)
    session.commit()

For more information, refer to Delete data.

Next steps

Need help?

Ask questions on TiDB Community, or create a support ticket.

Ask questions on TiDB Community, or create a support ticket.