title: VB.NET and LINQ - Group by in a DataTable
body: <p>I have a DataTable in VB.NET of this type:</p>
  
  <pre><code>"Yr","Mnth","Period","Amount"
  2016, 1, 2016-01, 550.36
  2016, 1, 2016-01, 9000.79
  2015, 12, 2015-12, 10000.30
  2015, 12, 2015-12, 20
  </code></pre>
  
  <p>What I want to do is to aggregate this data using LINQ like I would in SQL language:</p>
  
  <pre><code>SELECT Yr, Mnth, Period, SUM(Amount) AS Amount
  GROUP BY Yr, Mnth, Period;
  </code></pre>
  
  <p>I have tried to use LINQ in VB.NET but haven't been able to get it right.
  Can someone give me some insight?
  Thank you.</p>