What steps will reproduce the problem? import pyodbc

conn = pyodbc.connect("dsn=ms_2005;UID=scott;PWD=tiger")

cursor = conn.cursor()
cursor.execute("select cast(null as decimal)")
print cursor.fetchall()

What version of the product are you using? On what operating system? Run on Red Hat Enterprise Linux 6

Please provide any additional information below.

FreeTDS64 Driver TDS Version 8.0

Edit to original issue:

conn = pyodbc.connect("DRIVER={FreeTDS64};TDS_Version=8.0;...")