Connecting to SQL Server from Windows

Using an ODBC driver

There are actually many SQL Server ODBC drivers written and distributed by Microsoft:

• {SQL Server} - released with SQL Server 2000
• {SQL Native Client} - released with SQL Server 2005 (also known as version 9.0)
• {SQL Server Native Client 10.0} - released with SQL Server 2008
• {SQL Server Native Client 11.0} - released with SQL Server 2012
• {ODBC Driver 11 for SQL Server} - supports SQL Server 2005 through 2014
• {ODBC Driver 13 for SQL Server} - supports SQL Server 2005 through 2016

Note that the "SQL Server Native Client ..." and earlier drivers are deprecated and should not be used for new development.

The connection strings for all these drivers are essentially the same, for example:

DRIVER={ODBC Driver 11 for SQL Server};SERVER=test;DATABASE=test;UID=user;PWD=password

or, in Python:

conn = pyodbc.connect(
    r'DRIVER={ODBC Driver 11 for SQL Server};'
    r'SERVER=test;'
    r'DATABASE=test;'
    r'UID=user;'
    r'PWD=password'
    )

You can find out what drivers are available to your Python script by inspecting the list of driver names returned by pyodbc.drivers(). You can also navigate to Control Panel -> Administrative Tools -> Data Sources (ODBC) and inspect the "Drivers" tab in the ODBC Administrator application (odbcad32.exe), but be aware that there are separate 32-bit and 64-bit versions of the ODBC Administrator.

It's generally best to use the latest drivers you have, regardless of the version of SQL Server you are connecting to, because the drivers are largely backwards-compatible. However you may prefer to use the specific driver for your SQL Server instance.

Using a DSN

DSNs (or Data Source Names) allow you to define the ODBC driver, server, database, login credentials (possibly), and other connection attributes all in one place, so you don't have to provide them in your connection string. You can set up DSNs on your PC by using your ODBC Data Source Administrator window.

To get to your ODBC Data Source Administrator window, navigate to Control Panel -> Administrative Tools -> Data Sources (ODBC). Under 'User DSN' or 'System DSN' (depending on whether you want just you or everybody to be able to use this DSN) click on the 'Add...' button and follow the wizard instructions. Choose a driver that is suitable for the version of SQL Server you are connecting to, and add any other connection information that is relevant. Once you have created your new DSN, use it in the pyodbc.connect() function as follows:

conn = pyodbc.connect(r'DSN=mynewdsn;UID=user;PWD=password')

Attributes in the connection string will override any attributes in the DSN.

Other connection attributes

You can connect to your SQL Server instance using a trusted connection, i.e. without providing a login name and password, by using the Trusted_Connection attribute, e.g.:

conn = pyodbc.connect(
    r'DRIVER={ODBC Driver 11 for SQL Server};'
    r'SERVER=test;'
    r'DATABASE=test;'
    r'Trusted_Connection=True;'
    )

Adding the APP keyword allows you to provide a descriptive label (of up to 128 characters) for your database connection which is very handy for database administrators, e.g.:

conn = pyodbc.connect(
    r'DSN=mynewdsn;'
    r'UID=user;'
    r'PWD=password;'
    r'APP=Daily Incremental Backup;'
    )