title: add column dynamically with select query
body: <p>I have one table which has 20 columns default </p>
  
  <p>These 20 columns named as D1 D2 D3...D20 ,
  now with select query i want to add the other columns dynamically.. for ex D21 D22...D31,
  so how can i write a query to add this columns dynamically with incremented value..max limit is 31,please help</p>
  
  <p>default table columns<br>
       
          
         D1 D2 D3 D4 D5 D6 D7 D8 D9 D10 D11 D12 D13 D14 D15 D16 D17 D18 D19 D20
  <br>
  <br>
       now i want to add columns in continuity to D20  i.e D21 and so on upto D31 ,
       while selecting this columns the other column i.e fro D21 to D31 also get added and selected</p>
  
  <p>query is</p>
  
  <pre><code>select * ,'  ' as D21 from tbl1
  </code></pre>
  
  <p>this will give me all 20 columns upto D20 and one additional D21 i want it upto D31 without hardcoding other column name</p>