title: How can I filter a collection based on a day (rather than a date)?
body: <p>The end goal here is to get a list of customers whose birthday is today and send out a voucher code to them (which is also done programmatically).</p>
  
  <p>To do this, I need to grab all customers with a birthday today.  In SQL I would convert the <code>date</code> into a day and month and query that, but I'm unsure how to do that in a collection.  Currently I have:</p>
  
  <pre><code>$collection = Mage::getResourceModel('customer/customer_collection')
          -&gt;joinAttribute('dob','customer/dob', 'entity_id');
          -&gt;addAttributeToFilter('dob', '2015-10-02 00:00:00');
  </code></pre>
  
  <p>This only matches people with a DOB on 2/10/2015.  In this example, I need to match everyone with a date of birth of 2nd October, not just 2nd October 2015.  So, how can I omit the year and just include the day and month?</p>
  
  <p>I have been able to achieve this using a LIKE, but that seems unoptimised and I'd like to assume there's a far better way of doing this:</p>
  
  <pre><code>$collection = Mage::getResourceModel('customer/customer_collection')
          -&gt;joinAttribute('dob','customer/dob', 'entity_id')
          -&gt;addAttributeToFilter('dob', array('like' =&gt; '%-10-02 00:00:00'));
  </code></pre>