title: Mongodb query specific month|year not date
body: <p>How can I query a specific month in mongodb, not date range, I need month to make a list of customer birthday for current month.</p>
  
  <p>In SQL will be something like that:</p>
  
  <pre><code>SELECT * FROM customer WHERE MONTH(bday)='09'
  </code></pre>
  
  <p>Now I need to translate that in mongodb.
  Note: My dates are already saved in MongoDate type, I used this thinking that will be easy to work before but now I can't find easily how to do this simple thing.</p>