notmvp

SELECT `userID`, `productID`, `date`
  FROM (
    SELECT `userID`, `productID`, `date`,
           ROW_NUMBER() OVER `win` AS `row`
      FROM `table`
      WINDOW `win` AS (PARTITION BY `productID` ORDER BY `date` DESC)
  ) AS `t`
  WHERE `row` = 1

XNamespace aw = "http://www.adventure-works.com";
XElement root = new XElement(aw + "Root",
    new XAttribute(XNamespace.Xmlns + "aw", "http://www.adventure-works.com"),
    new XElement(aw + "Child", "child content")
);
Console.WriteLine(root);

<aw:Root xmlns:aw="http://www.adventure-works.com">
  <aw:Child>child content</aw:Child>
</aw:Root>