title: MySQL query to get count of only new users each day
body: <p>I have a table of call records, 
  I need to know for each day how many people are first time calling every day,</p>
  
  <p>Note: they called the selected day, but never before that day.
  I managed to have this working.</p>
  
  <pre><code>SELECT * FROM call_history GROUP BY caller_id HAVING SUBSTR(MIN(call_date), 1, 10) = SUBSTR(NOW(), 1, 10) 
  </code></pre>
  
  <p>This query gives me all the people who called today (or any date I put in instead of NOW) but never called before,
  I need to find a way to get the results for all days in a single query and not ask day by day,</p>
  
  <p>result should be like that:</p>
  
  <pre><code>2013-01-01, 10 new callers
  2013-01-01, 15 new callers
  2013-01-01, 22 new callers
  2013-01-01, 4 new callers
  </code></pre>
  
  <p>and so on....</p>
  
  <p>Thank you!</p>