title: Copy Specific Dataset Columns to Datatable
body: <p>i have a DataSet which reads xml data and it has almost 20 columns,
  i need 5 columns from the DataSet .
  i have tried at my level but not able to get the DataTable with the specific columns i need.
  some codes which i tried are : </p>
  
  <pre><code>DataTable dt = new DataTable();  //dt is blank DataTable 
  DataSet ds = new DataSet();  //ds is existing DataSet which has single table in it
  dt.Columns[0]=dst4.Tables[0].Columns[0];               
  dt.Columns.Add(dst4.Tables[0].Columns[0]);  
  ds.Tables.Add(dt)
  dst4.Tables.Columns.Add(dt);
  </code></pre>