title: How can I get a sum for the column "pieces" in a datatable?
body: <p>How can I get a sum for the column "pieces" in a datatable? Say I had the following table. How can I calculate the "total" pieces for article="milk" and artno="15"? </p>
  
  <pre><code>Columns:   article     artno    pieces
  Rows:
  1          milk        15       1
  2          water       12       1
  3          apple       13       2
  4          milk        15       1
  5          milk        16       1
  6          bread       11       2
  7          milk        16       4
  </code></pre>
  
  <p>The Result of the my new DataTable should be this:</p>
  
  <pre><code>Columns:   article     artno    pieces
  Rows:
  1          bread       11       2
  2          water       12       1
  3          apple       13       2
  4          milk        15       2
  5          milk        16       5
  </code></pre>
  
  <p>My Code:</p>
  
  <pre><code>foreach (DataRow foundDataRow in foundRows1)
  {
      int i = 0;
      foreach (DataRow dataRow in foundRows2)
      {
          if (object.Equals(dataRow.ItemArray[0], foundDataRow.ItemArray[0])
              &amp;&amp; object.Equals(dataRow.ItemArray[3], foundDataRow.ItemArray[3]))
          {
              i = i + Convert.ToInt16(dataRow.ItemArray[4]);
          }
      }
      Debug.Print(i.ToString());
  }
  </code></pre>
  
  <p>Sorry, but i'm new DataBase developer and my english speak language is not so good.</p>