title: Issue with querying Teradata in Python/Pyodbc
body: <p>I'm trying to query a Teradata database in Python with PyODBC.
  The connection to database is established alright; however, when I try to fetch result, I ran into this error "Invalid literal for Decimal: u''". Help please.</p>
  
  <p>I am on RHEL6, with Python 2.7.3</p>
  
  <p>Here is the code and result:</p>
  
  <pre><code>import pyodbc
  
  sql = "select * from table"
  
  pyodbc.pooling = False
  cnx = pyodbc.connect("DRIVER={Teradata};DBCNAME=host;DATABASE=database;   AUTHENTICATION=LDAP;UID=user;PWD=password", autocommit=True, ANSI=True)
  cursor = cnx.cursor()
  rows = cursor.execute(sql).fetchone()
  </code></pre>
  
  <hr>
  
  <pre><code>InvalidOperation                          Traceback (most recent call last)
  &lt;ipython-input-25-f2a0c81ca0e4&gt; in &lt;module&gt;()
  ----&gt; 1 test.fetchone()
  
  /usr/local/lib/python2.7/decimal.pyc in __new__(cls, value, context)
      546                     context = getcontext()
      547                 return context._raise_error(ConversionSyntax,
  --&gt; 548                                 "Invalid literal for Decimal: %r" % value)
      549 
      550             if m.group('sign') == "-":
  
  /usr/local/lib/python2.7/decimal.pyc in _raise_error(self, condition, explanation, *args)
     3864         # Errors should only be risked on copies of the context
     3865         # self._ignored_flags = []
  -&gt; 3866         raise error(explanation)
     3867 
     3868     def _ignore_all_flags(self):
  
  InvalidOperation: Invalid literal for Decimal: u''
  </code></pre>