Connect to SQL Server using SQLAlchemy - sql-server

Question

I'm trying to connect to a SQL Server Express database using SQLALchemy and pyodbc, but I'm continuously getting the error:
(pyodbc.Error) ('IM002', '[IM002] [unixODBC][Driver Manager]Data
source name not found, and no default driver specified (0)
(SQLDriverConnect)')
And I really don't understand if my engine url is wrong or what else.
My scenario is the following:
I'm on a Mac
I have a docker container (based on a Debian image with unixodbc and unixodbc-dev) in which my python app tries to connect to...
a virtualbox virtual machine running windows 8 with SQL express 2014...
I configured a user for the SQL express, with SQL Server authentication:
user: ar_user
password: ar_psw
...then:
I configured TCP ports as 1433 and disabled dynamic ports (SQL Server Configuration Manager > Network Configurations > Protocols).
I turned off Windows Firewall.
I used an Host-only adapter for the VM running windows8
now...
The VM is accessible from the host (my mac), since a:
ping -c 3 vm-ip
succeed!
But although I tried every possible permutation of user, password, ip, server name and port:
'mssql+pyodbc://ar_user:ar_psw#vm-ip/master'
'mssql+pyodbc://ar_user:ar_psw#vm-ip:1433/master'
'mssql+pyodbc://IE10WIN8\\SQLEXPRESS'
'mssql+pyodbc://ar_user:ar_psw#IE10WIN8\\SQLEXPRESS'
'mssql+pyodbc://ar_user:ar_psw#IE10WIN8\\SQLEXPRESS:1433'
'mssql+pyodbc://ar_user:ar_psw#IE10WIN8\\SQLEXPRESS:1433/master'
...and many more!
I always get the "datasource not found error".
What should I do?
ps: the vm is pingable even in the docker container!
UPDATE (solved but not 100%):
I solved in this way:
I configured FreeTDS driver using /etc/odbcinst.ini in this way:
[FreeTDS]
Description = TDS driver (Sybase/MS SQL)
Driver = /usr/lib/x86_64-linux-gnu/odbc/libtdsodbc.so
Setup = /usr/lib/x86_64-linux-gnu/odbc/libtdsS.so
client charset = UTF-8
and in /etc/freetds/freetds.conf:
[global]
tds version = 7.3
client charset = UTF-8
Then I created the engine using the following string:
'mssql+pyodbc://my_user:my_psw#machine_ip:1433/my_db?driver=FreeTDS'
It seems to work properly, but I get this warning:
SAWarning: Unrecognized server version info '95.12.255'. Version
specific behaviors may not function properly. If using ODBC with
FreeTDS, ensure TDS_VERSION 7.0 through 7.3, not 4.2, is configured in
the FreeTDS configuration.
I also defined the TDS version using environment variables but it doesn't fix the issue... any idea?

Answer 1

I wrote a tutorial here of how to do this. Essentially, you need to:
brew install unixodbc
brew install freetds --with-unixodbc
Add the freetds driver to odbcinst.ini
Add a DSN (Domain Source Name) to odbc.ini named "MY_DSN"
pip install pyodbc
e = create_engine("mssql+pyodbc://username:password#MY_DSN")
The walkthrough here does a much more thorough job of explaining this, including issues with SQL Server/FreeTDS Protocol Version Compatibility.