title: Set value of each DataTable row in specific column
body: <p>I'm having some problem while trying to set column value. </p>
  
  <p>I'v had a dataTable which get some values from SQL and then im adding two new columns by :</p>
  
  <pre><code>        dataTable.Columns.Add("dest", typeof(int));
  
          dataTable.Columns.Add("amount", typeof(int));
  </code></pre>
  
  <p>Which works great but now i want to put 0 in every row in column name dest - and later user will edit this, and then i want to set amount value as</p>
  
  <pre><code>       amount = all(this column is in dataTable before I add these 2 columns) + dest;
  </code></pre>