Cannot establish connection to sql-server using pyodbc on Windows 7

You're using a connection string of 'DRIVER={SQL Server};SERVER=server;DATABASE=db1;UID=uname;PWD=pword;Trusted_Connection=yes', you're trying to connect to a server called server, a database called db1, etc. It doesn't use the variables you set before, they're not used.

It's possible to pass the connection string parameters as keyword arguments to the connect function, so you could use:

cnxn = pyodbc.connect(driver='{SQL Server}', host=server, database=db1,
                      trusted_connection=tcon, user=uname, password=pword)

I had faced this error due to another reason.
It was because my server had a "port" apart from the address.
I could fix that by assigning the following value to "Server" parameter of the connection string.

"...;Server=<server_name>,<port#>;..."

Note that it is a 'comma' and not 'colon'/'period'

I had the same error message and in my case the issue was the [SQL Server] drivers required TLS 1.0 which is disabled on my server. Changing to the newer version of the SNAC, SQL Server Native Client 11.0 fixed the problem.

So my connection string looks like:

cnxn = pyodbc.connect(driver='{SQL Server Native Client 11.0}', 
                      host=server, database=db1, trusted_connection=tcon,
                      user=uname, password=pword)