title: Why is "00:00:00" seen as being the same thing as NULL in MYSQL Time field?
body: <p>I have a mysql field called "time_of_birth" that is definitely set to NULL.</p>
  
  <p>I have a PHP check on that field like this:</p>
  
  <pre><code>if ($row['time_of_birth'] !== "00:00:00") {
  //do this stuff
  } else {
  //do something else
  }
  </code></pre>
  
  <p>For that field that is definitely set to NULL, it's doing the "do this stuff".  Isn't NULL different than "00:00:00"?  I would expect it to do "do something else" because it's not exactly equal to "00:00:00".  </p>
  
  <p>What am I missing here?</p>