Allow a caller-supplied Application Name (APP) instead of hardcoding "MSSQL-Python" #649

Summary

mssql_python does not let an application set its own Application Name on a connection. The driver reserves the APP connection-string parameter and always overrides it with the literal "MSSQL-Python", so every connection reports program_name = MSSQL-Python in sys.dm_exec_sessions and in the Fabric / SQL Server query history.

Details (as of mssql-python 1.9.0)

• connection_string_parser.py removes APP from the user-supplied connection string (it is in _RESERVED_PARAMETERS).
• connection.py raises ValueError if APP is passed via connect() kwargs (reserved parameter).
• connection.py then unconditionally sets, after processing kwargs:

  # Step 4: Add Driver and APP (always controlled by the driver).
  normalized_params["Driver"] = "ODBC Driver 18 for SQL Server"
  normalized_params["APP"] = "MSSQL-Python"

So there is currently no supported way (connection string or kwarg) for a caller to set the application name.

Why this matters

• Tools and services built on mssql_python cannot identify themselves in sys.dm_exec_sessions.program_name or in query history; everything is attributed to MSSQL-Python, which makes per-application monitoring, auditing and troubleshooting much harder.
• Microsoft Fabric (and SQL Server) support workload classification / routing by Application Name. With the name pinned to MSSQL-Python, callers cannot route their workloads to a custom classifier.
• The ODBC Driver itself, and pyodbc, both honour an APP= value supplied by the caller.

Request

Let callers set the application name, while keeping MSSQL-Python as the default when none is supplied. For example:

• honour an APP=... value present in the connection string, or
• accept an application_name="..." (or app="...") keyword on connect() / Connection(...),

falling back to "MSSQL-Python" only when the caller did not provide one.

Repro

import mssql_python
conn = mssql_python.connect("Server=...;Database=...;Encrypt=yes;APP=MyApp")
cur = conn.cursor()
cur.execute("SELECT program_name FROM sys.dm_exec_sessions WHERE session_id = @@SPID")
print(cur.fetchone())  # -> ('MSSQL-Python',)  (expected: 'MyApp')

Thanks for the driver, otherwise it has been a pleasure to build on.