title: Oracle: getting maximum value of a group?
body: <p>Given a table like this, what query will the most recent calibration information for each monitor?  In other words, I want to find the maximum date value for each of the monitors. Oracle-specific functionality is fine for my application.</p>
  
  <pre><code>monitor_id     calibration_date  value
  ----------     ----------------  -----
  1              2011/10/22        15
  1              2012/01/01        16
  1              2012/01/20        17
  2              2011/10/22        18
  2              2012/01/02        19
  </code></pre>
  
  <p>The results for this example would look like this:</p>
  
  <pre><code>1  2012/01/20 17
  2  2012/01/02 19
  </code></pre>