Get birthday with a query : <p>I have problems to get age of certain dates.</p>

<pre><code>SELECT birthday, DATE_FORMAT(FROM_DAYS(TO_DAYS(NOW())-TO_DAYS(birthday)), '%Y')+0 AS age FROM users;
</code></pre>

<p>The result is:</p>

<pre><code>| 27-07-1955 | NULL |
</code></pre>

<p>What's wrong in this select?</p>
