title: RANKing in group by in oracle
body: <p>I have a query </p>
  
  <pre><code>Select age,qualification,sum(income) as total_income  from employee
  group by age,qualification;
  </code></pre>
  
  <p>I want to find rank on based total_income for the group of age and qualification. </p>
  
  <p>For example</p>
  
  <pre><code>19|Grad|5000|rank:1
  19|Grad|4000|rank:2
  19|Grad|3000|rank:3
  26|Grad|6000|rank:1
  26|Grad|5000|rank:2
  26|PosG|8000|rank:1
  26|PosG|6000|rank:2
  </code></pre>
  
  <p>Can I do it in Oracle? I tried with partition by but not able to figure it out.</p>