title: How to make a null safe condition?
body: <p>Here is the logic:</p>
  
  <pre><code>. . . WHERE hh.deleted = 0 OR hh.deleted IS NULL . . .
  </code></pre>
  
  <p>I want to make it more neat and short, so here is the new version:</p>
  
  <pre><code>. . . WHERE hh.deleted &lt;=&gt; 0 . . .
  </code></pre>
  
  <p>But the result is not the same .. Any idea why? and what's the different?</p>