Why do psycopg2 and pyodbc connect to databases differently? And how could I translate a connection? - postgresql

Question

So I've been trying to find a good module for querying information at my company's POSTGRES databases.
There are so many modules around, but I can only seem to get pyodbc to work.
Why is pyodbc's form of connecting different than psycopg2, which seems to be the superior module?
And how would I translate my connection query from one to the other?
I can connect to my company's server like this with **pyodbc** no problem.
pyodbc.connect("DRIVER={SQLServer};SERVER=some\servername;DATABASE=someDatabaseName;Trusted_Connection=yes")
But this doesn't work for psycopg2 with:
psycopg2.connect(database="someDatabaseName", host="some\servername")
psycopg2 returns:
OperationalError: could not translate host name "some\servername" to
address: Unknown host
Of topic:
I hope someone can help, my heroku server simply does not want to install pyodbc

Answer 1

pyodbc is a Python module that can be used to connect to many different types of databases using the ODBC API. Specifically, pyodbc is compliant with the DB API 2.0 spec.
Your working code sample uses an ODBC implementation of a SQL Server driver to connect to a SQL Server instance. Drivers are DBMS-specific, ODBC is not.

Answer 2

I had the same issue. I wanted to re-use the ODBC connection details as used by pyodbc to connect to a PostgreSQL DB using psycopg2.
The connection details can be found in the Windows registry.
Basically, the following code will extract the required details from the registry:
import os
from winreg import (
ConnectRegistry,
HKEY_LOCAL_MACHINE,
OpenKeyEx,
QueryValueEx,
)
def odbc_dsn_2_psyopg2dsn(odbc_dsn, user, pwd ):
"""
This function converts a windows ODBC DSN to a dsn
that can be used by psycopg2.
It reads connection parameters from the windows registry,
username and password are often not in there,
and can be supllied as parameters.
"""
# get hostname, port, sslmode from odbc registry
hreg = ConnectRegistry(None,HKEY_LOCAL_MACHINE)
key = f"SOFTWARE\\ODBC\\ODBC.INI\\{odbc_dsn}"
hkey = OpenKeyEx(hreg, key)
hostname = QueryValueEx(hkey, "Servername")[0]
portnumber = QueryValueEx(hkey, "Port")[0]
sslmode = QueryValueEx(hkey, "SSLmode")[0]
database = QueryValueEx(hkey, "Database")[0]
#set defaults for portnmumber and SSL mode (my pref, maybe in your case there are in the registry too)
if not portnumber:
portnumber = "5432"
if not sslmode:
sslmode = 'Prefer'
# using all of the above, create psycopg2 connection-dsn
return f"dbname={database} user={user} password={pwd} host={hostname} port={portnumber} sslmode={sslmode}"