title: How to fetch last two quarter data from Oracle table
body: <p>I have one table named "Quarter_revenue". Sample of the table structure is below</p>
  
  <pre>
  Year    Quarter Revenue
  2017    Q1  10000
  2017    Q1  20000
  2017    Q2  30000
  2017    Q2  40000
  2017    Q3  50000
  2017    Q3  60000
  2017    Q4  70000
  2017    Q4  80000
  2016    Q1  90000
  2016    Q1  100000
  2016    Q2  110000
  2016    Q2  120000
  2016    Q3  130000
  2016    Q3  140000
  2016    Q4  150000
  2016    Q4  160000
  2015    Q1  170000
  2015    Q1  180000
  2015    Q2  190000
  2015    Q2  200000
  2015    Q3  210000
  2015    Q3  220000
  2015    Q4  230000
  2015    Q4  240000
  </pre>
  
  <p>There is no date column in this table. I want to fetch last two quarter data from this table. This table will update in every quarter. Please help me on that..</p>