import sys
from os import getenv
import pymssql
import time
import numpy as np
import array
from re import sub
import openpyxl
import subprocess

# Definition vo Variablen und Felder
...
conn = pymssql.connect(server="server" , user="mustermann", password="passwort")
cursor = conn.cursor()
cursor.execute("""SELECT convert(NVARCHAR,b.[Posting Date],104) as Datum
	   ,b.[Posting Date]
	   ,[No_] as Artikel#
        ,a.[DescriptionFUll]
	    ,b.[Document No_]
		,b.[Entry Type]
		,"Vorgang" =
		case
	      when [Entry Type]=0 then 'Einkauf'
		  when [Entry Type]=1 then 'Verkauf'
		  when [Entry Type]=2 then 'Zugang'
		  when [Entry Type]=3 then 'Abgang'
		  when [Entry Type]=4 then 'Umlagerung'
		  when [Entry Type]=5 then 'Verbrauch'
		  when [Entry Type]=6 then 'Istmeldung'
		  when [Entry Type]=7 then 'N.N'
		  when [Entry Type]=8 then 'Verbrauch für Montage'
		  when [Entry Type]=9 then 'Montage-Istmeldung'
		end
		,cast(round(b.[Quantity],2,2) as real) as Menge
      ,[Base Unit of Measure]
      ,cast(round([Unit Cost],2) as real) as 'EuroProEinheit'
      ,[Blocked]
      ,cast(round([Lot Size],2,2) as real) as Losgröße
      ,cast(round([Safety Stock Quantity],2,2)as real) as Sich_Bestand     
	  ,[Zeichnungsnummer]
      ,[Inventur]
      ,[Blocked Purchase]
FROM [Mustermann BC].[dbo].[Mustermann_GmbH$Item] as a
   LEFT JOIN [Mustermann BC].[dbo].[Mustermann_GmbH$Item Ledger Entry] AS b ON a.No_ = b.[Item No_]
where No_ like '894204'""")

cursor.execute('SELECT * FROM persons WHERE salesrep=%s', 'John Doe')

Quote:Cursor.execute(operation)
Cursor.execute(operation, params)

operation is a string and params, if specified, is a simple value, a tuple, a dict, or None.

Performs the operation against the database, possibly replacing parameter placeholders with provided values. This should be preferred method of creating SQL commands, instead of concatenating strings manually, what makes a potential of SQL Injection attacks. This method accepts formatting similar to Python’s builtin string interpolation operator. However, since formatting and type conversion is handled internally, only the %s and %d placeholders are supported. Both placeholders are functionally equivalent.

Keyed placeholders are supported if you provide a dict for params.

If you call execute() with one argument, the % sign loses its special meaning, so you can use it as usual in your query string, for example in LIKE operator. See the examples.

You must call Connection.commit() after execute() or your data will not be persisted in the database. You can also set connection.autocommit if you want it to be done automatically. This behaviour is required by DB-API, if you don’t like it, just use the _mssql module instead.

Artikelnummer='894204'	
# ^^^^^^^^^^^^^^^^^^^
# "Artikelnummer" as a string
conn = pymssql.connect(server="server" , user="mustermann", password="passwort")
cursor = conn.cursor()
cursor.execute("""SELECT convert(NVARCHAR,b.[Posting Date],104) as Datum
	   ,b.[Posting Date]
	   ,a.[No_] as Artikel#
        ,a.[DescriptionFUll]
	    ,b.[Document No_]
		,b.[Entry Type]
		,"Vorgang" =
		case
	      when [Entry Type]=0 then 'Einkauf'
		  when [Entry Type]=1 then 'Verkauf'
		  when [Entry Type]=2 then 'Zugang'
		  when [Entry Type]=3 then 'Abgang'
		  when [Entry Type]=4 then 'Umlagerung'
		  when [Entry Type]=5 then 'Verbrauch'
		  when [Entry Type]=6 then 'Istmeldung'
		  when [Entry Type]=7 then 'N.N'
		  when [Entry Type]=8 then 'Verbrauch für Montage'
		  when [Entry Type]=9 then 'Montage-Istmeldung'
		end
		,cast(round(b.[Quantity],2,2) as real) as Menge
      ,[Base Unit of Measure]
      ,cast(round([Unit Cost],2) as real) as 'EuroProEinheit'
      ,a.[Blocked]
      ,cast(round([Lot Size],2,2) as real) as Losgröße
      ,cast(round([Safety Stock Quantity],2,2)as real) as Sich_Bestand     
	  ,[Zeichnungsnummer]
      ,[Inventur]
      ,[Blocked Purchase]
	  ,Lieferant.No_
	  ,Lieferant.Name
	  ,Lieferant.City
FROM [Mustermann].[dbo].[Mustermann_GmbH$Item] as a
   LEFT JOIN [Mustermann].[dbo].[Mustermann_GmbH$Item Ledger Entry] AS b ON a.No_ = b.[Item No_]
   LEFT JOIN [Mustermann].[dbo].[Mustermann_GmbH$Vendor] as Lieferant on a.[Vendor No_] = Lieferant.No_
   where a.No_ like %s""", Artikelnummer)
#                   ^^     ^^^^^^^^^^^^^
#  format and the variable Artikelnummer again