title: Whats wrong with this MYSQL query
body: <p>I have the following SQL query , it seems to run ok , but i am concerned as my site grows it may not perform as expected ,I would like some feeback as to how effective and efficient this query really is:</p>
  
  <p><code>select * from articles where category_id=XX AND city_id=XXX GROUP BY user_id ORDER BY created_date DESC LIMIT 10;</code></p>
  
  <p>Basically what i am trying to achieve - is to get the newest articles by created_date limited to 10 , articles must only be selected if the following criteria are met :</p>
  
  <ol>
  <li>City ID must equal the given value</li>
  <li>Category ID must equal the given value</li>
  <li>Only one article per user must be returned</li>
  <li>Articles must be sorted by date and only the top 10 latest articles must be returned</li>
  </ol>