title: postgresql NOT ILIKE clause does not include null string values
body: <p>Here's the setup on Postgresql 9.2.4:</p>
  
  <pre><code>CREATE TABLE table (
      id integer NOT NULL,
      some_text text
  );
  </code></pre>
  
  <p>Now we enter one record, with a null or empty string for <code>some_text</code>, so that when we query:</p>
  
  <pre><code>SELECT * FROM table WHERE some_text IS NULL;
  </code></pre>
  
  <p>I get the entry back. So far so good.</p>
  
  <p>However, when I query:</p>
  
  <pre><code>SELECT * FROM table WHERE some_text NOT ILIKE "%anything%';
  </code></pre>
  
  <p>I find that nothing was returned. Why is that? I expect a null or empty string to be "not like <code>anything</code>".</p>