title: NoneType object is not iterable error in pandas
body: <p>I am trying to pull some data from a stored proc on a sql server using python.</p>
  
  <p>Here is my code:</p>
  
  <pre><code>import datetime as dt
  import pyodbc
  import pandas as pd
  
  conn = pyodbc.connect('Trusted_Connection=yes', driver = '{SQL Server Native client 11.0}',server = '*****, database = '**')
  
  pd.read_sql("EXEC ******** '20140528'",conn)
  </code></pre>
  
  <p>I get the error: TypeError: 'NoneType' object is not iterable</p>
  
  <p>I suspect this is because I have a cell in the sql table with value NULL but not sure if that's the true reason why I am getting the error. I have run many sql statements using the same code without any errors.</p>
  
  <p>Here's the traceback:</p>
  
  <pre><code>In[39]: pd.read_sql("EXEC [dbo].[] '20140528'",conn)
  Traceback (most recent call last):
    File "C:*", line 3032, in run_code
      exec(code_obj, self.user_global_ns, self.user_ns)
    File "&lt;ipython-input-39-68fb1c956dd7&gt;", line 1, in &lt;module&gt;
      pd.read_sql("EXEC [dbo].[] '20140528'",conn)
    File "C:*", line 467, in read_sql
      chunksize=chunksize
    File "c:***", line 1404, in read_query
      columns = [col_desc[0] for col_desc in cursor.description]
  TypeError: 'NoneType' object is not iterable
  </code></pre>