 <p>A comment does nothing (but your database driver might complain if there is not command at all):</p> <pre><code>/* Hello, world! */ </code></pre> <p>Unknown <a href="http://www.sqlite.org/pragma.html" rel="nofollow">PRAGMA</a> statements are ignored, and do not return anything:</p> <pre><code>PRAGMA testing_porpoises; </code></pre> <p>If you need a statement that returns an empty result set, you need a SELECT:</p> <pre><code>SELECT 0 WHERE 0; </code></pre>