How to configure a MSSQL Datasource

This guide shows how to connect to a MSSQL Datasource. Great Expectations uses SqlAlchemy to connect to MSSQL, and relies further on the PyODBC driver.

Prerequisites: This how-to guide assumes you have already:

  • Set up a working deployment of Great Expectations

  • Obtained database credentials for MSSQL, including username, password, hostname, and database.


  1. Install the required ODBC drivers

    Follow guides from Microsoft according to your operating system. We have included additional links to relevant resources for connecting to MSSQL databases in the Additional Information section below.

  2. Install the required python modules

    If you have not already done so, install required modules for connecting to mysql.

    pip install sqlalchemy
    pip install pyodbc
  3. Run datasource new

    From the command line, run:

    great_expectations datasource new
  4. Choose “Relational database (SQL)”

    What data would you like Great Expectations to connect to?
        1. Files on a filesystem (for processing with Pandas or Spark)
        2. Relational database (SQL)
    : 2
  5. Choose ‘other’ and provide a connection string

    Which database backend are you using?
        1. MySQL
        2. Postgres
        3. Redshift
        4. Snowflake
        5. BigQuery
        6. other - Do you have a working SQLAlchemy connection string?
    : 6
  6. Give your Datasource a name

    When prompted, provide a custom name for your Snowflake data source, or hit Enter to accept the default.

    Give your new Datasource a short name.
     [my_database]: mssql_db
  7. Enter connection information

    When prompted, enter a connection string to use to connect to your datasource. Note that we add a query parameter to our connection string to specify the driver: driver=ODBC Driver 17 for SQL Server

    Next, we will configure database credentials and store them in the `my_database` section
    of this config file: great_expectations/uncommitted/config_variables.yml:
    What is the url/connection string for the sqlalchemy connection?
    : mssql+pyodbc://<<username>>:<<password>>@<<host>>:<<port>>/<<database>>?driver=ODBC Driver 17 for SQL Server&charset=utf&autocommit=true
  8. Save your new configuration

    Great Expectations will now add a new Datasource 'mssql_db' to your deployment, by adding this entry to your great_expectations.yml:
        credentials: ${my_database}
          class_name: SqlAlchemyDataset
          module_name: great_expectations.dataset
        class_name: SqlAlchemyDatasource
        module_name: great_expectations.datasource
    The credentials will be saved in uncommitted/config_variables.yml under the key 'mssql_db'

Additional notes

The following blog post provides a useful overview of using SqlAlchemy to connect to MSSQL.