Learn more
 

How to use SQLAlchemy ORM to access Snowflake Data in Python


Create Python applications and scripts that use SQLAlchemy Object-Relational Mappings of Snowflake data.

The rich ecosystem of Python modules lets you get to work quickly and integrate your systems effectively. With the CData Python Connector for Snowflake and the SQLAlchemy toolkit, you can build Snowflake-connected Python applications and scripts. This article shows how to use SQLAlchemy to connect to Snowflake data to query, update, delete, and insert Snowflake data.

With built-in optimized data processing, the CData Python Connector offers unmatched performance for interacting with live Snowflake data in Python. When you issue complex SQL queries from Snowflake, the CData Connector pushes supported SQL operations, like filters and aggregations, directly to Snowflake and utilizes the embedded SQL engine to process unsupported operations client-side (often SQL functions and JOIN operations).

About Snowflake Data Integration

CData simplifies access and integration of live Snowflake data. Our customers leverage CData connectivity to:

  • Reads and write Snowflake data quickly and efficiently.
  • Dynamically obtain metadata for the specified Warehouse, Database, and Schema.
  • Authenticate in a variety of ways, including OAuth, OKTA, Azure AD, Azure Managed Service Identity, PingFederate, private key, and more.

Many CData users use CData solutions to access Snowflake from their preferred tools and applications, and replicate data from their disparate systems into Snowflake for comprehensive warehousing and analytics.

For more information on integrating Snowflake with CData solutions, refer to our blog: https://www.cdata.com/blog/snowflake-integrations.


Getting Started


Connecting to Snowflake Data

Connecting to Snowflake data looks just like connecting to any relational data source. Create a connection string using the required connection properties. For this article, you will pass the connection string as a parameter to the create_engine function.

To connect to Snowflake:

  1. Set User and Password to your Snowflake credentials and set the AuthScheme property to PASSWORD or OKTA.
  2. Set URL to the URL of the Snowflake instance (i.e.: https://myaccount.snowflakecomputing.com).
  3. Set Warehouse to the Snowflake warehouse.
  4. (Optional) Set Account to your Snowflake account if your URL does not conform to the format above.
  5. (Optional) Set Database and Schema to restrict the tables and views exposed.

See the Getting Started guide in the CData driver documentation for more information.

Follow the procedure below to install SQLAlchemy and start accessing Snowflake through Python objects.

Install Required Modules

Use the pip utility to install the SQLAlchemy toolkit and SQLAlchemy ORM package:

pip install sqlalchemy pip install sqlalchemy.orm

Be sure to import the appropriate modules:

from sqlalchemy import create_engine, String, Column from sqlalchemy.ext.declarative import declarative_base from sqlalchemy.orm import sessionmaker

Model Snowflake Data in Python

You can now connect with a connection string. Use the create_engine function to create an Engine for working with Snowflake data.

NOTE: Users should URL encode the any connection string properties that include special characters. For more information, refer to the SQL Alchemy documentation.

engine = create_engine("snowflake:///?User=Admin&Password=test123&Server=localhost&Database=Northwind&Warehouse=TestWarehouse&Account=Tester1")

Declare a Mapping Class for Snowflake Data

After establishing the connection, declare a mapping class for the table you wish to model in the ORM (in this article, we will model the Products table). Use the sqlalchemy.ext.declarative.declarative_base function and create a new class with some or all of the fields (columns) defined.

base = declarative_base() class Products(base): __tablename__ = "Products" Id = Column(String,primary_key=True) ProductName = Column(String) ...

Query Snowflake Data

With the mapping class prepared, you can use a session object to query the data source. After binding the Engine to the session, provide the mapping class to the session query method.

Using the query Method

engine = create_engine("snowflake:///?User=Admin&Password=test123&Server=localhost&Database=Northwind&Warehouse=TestWarehouse&Account=Tester1") factory = sessionmaker(bind=engine) session = factory() for instance in session.query(Products).filter_by(Id="1"): print("Id: ", instance.Id) print("ProductName: ", instance.ProductName) print("---------")

Alternatively, you can use the execute method with the appropriate table object. The code below works with an active session.

Using the execute Method

Products_table = Products.metadata.tables["Products"] for instance in session.execute(Products_table.select().where(Products_table.c.Id == "1")): print("Id: ", instance.Id) print("ProductName: ", instance.ProductName) print("---------")

For examples of more complex querying, including JOINs, aggregations, limits, and more, refer to the Help documentation for the extension.

Insert Snowflake Data

To insert Snowflake data, define an instance of the mapped class and add it to the active session. Call the commit function on the session to push all added instances to Snowflake.

new_rec = Products(Id="placeholder", Id="1") session.add(new_rec) session.commit()

Update Snowflake Data

To update Snowflake data, fetch the desired record(s) with a filter query. Then, modify the values of the fields and call the commit function on the session to push the modified record to Snowflake.

updated_rec = session.query(Products).filter_by(SOME_ID_COLUMN="SOME_ID_VALUE").first() updated_rec.Id = "1" session.commit()

Delete Snowflake Data

To delete Snowflake data, fetch the desired record(s) with a filter query. Then delete the record with the active session and call the commit function on the session to perform the delete operation on the provided records (rows).

deleted_rec = session.query(Products).filter_by(SOME_ID_COLUMN="SOME_ID_VALUE").first() session.delete(deleted_rec) session.commit()

Free Trial & More Information

Download a free, 30-day trial of the CData Python Connector for Snowflake to start building Python apps and scripts with connectivity to Snowflake data. Reach out to our Support Team if you have any questions.

Ready to get started?

Download a free trial of the Snowflake Connector to get started:

 Download Now

Learn more:

Snowflake Enterprise Data Warehouse Icon Snowflake Python Connector

Python Connector Libraries for Snowflake Enterprise Data Warehouse Data Connectivity. Integrate Snowflake Enterprise Data Warehouse with popular Python tools like Pandas, SQLAlchemy, Dash & petl.

In this article

Related articles