title: Python SQL Select with possible NULL values
body: <p>I'm new to python and have hit a problem with an SQL query I'm trying to perform.</p>
  
  <p>I am creating an SQL SELECT statement that is populated with values from an array as follows:</p>
  
  <pre><code>ret = conn.execute('SELECT * FROM TestTable WHERE a = ? b = ? c = ?', *values)
  </code></pre>
  
  <p>This works ok where I have real values in the values array. However in some cases an individual entry in values may be set to None. The query then fails because the "= NULL" test does not work since the test should be IS NULL.</p>
  
  <p>Is there an easy way around this?</p>