title: Why does SQLite not use indexes when you use 'IS' instead of '='?
body: <p>This query will not use the index: <code>SELECT * FROM baz WHERE id IS '123'</code></p>
  
  <p><a href="http://sqlfiddle.com/#!7/7e299/2" rel="nofollow">http://sqlfiddle.com/#!7/7e299/2</a></p>
  
  <p>This query will use the index: <code>SELECT * FROM baz WHERE id='123'</code></p>
  
  <p><a href="http://sqlfiddle.com/#!7/7e299/1" rel="nofollow">http://sqlfiddle.com/#!7/7e299/1</a></p>
  
  <p>Why?? </p>
  
  <p>EDIT: I realize there is the stupid answer of expanding the IS to get the correct effect (i.e. making the query <code>SELECT * FROM baz WHERE id='123' OR '123' IS NULL</code>, but I am still curious why this is the case.</p>