title: Group By Multiple Columns
body: <p>How can I do GroupBy multiple columns in LINQ</p>
  <p>Something similar to this in SQL:</p>
  <pre><code>SELECT * FROM &lt;TableName&gt; GROUP BY &lt;Column1&gt;,&lt;Column2&gt;
  </code></pre>
  <p>How can I convert this to LINQ:</p>
  <pre><code>QuantityBreakdown
  (
      MaterialID int,
      ProductID int,
      Quantity float
  )
  
  INSERT INTO @QuantityBreakdown (MaterialID, ProductID, Quantity)
  SELECT MaterialID, ProductID, SUM(Quantity)
  FROM @Transactions
  GROUP BY MaterialID, ProductID
  </code></pre>