title: How to get unique id count by month and year?
body: <p>I have a query that is counting the total user_id 
  but I would like it to get the count for each month/year 
  using the column start_date. </p>
  
  <p>start_date is a collumn in agentdispodetail and datetype.</p>
  
  <p>start_date is usually like:
  2014-11-21 14:47:15.680</p>
  
  <pre><code>select distinct user_id, count(*) as total_id
    from agentdispodetail
    group by  user_id
  </code></pre>
  
  <p>I use sql 2012.</p>