Listing 5: Adding COMPUTE and COMPUTE BY
SELECT OD.ProductID AS 'Product ID'
	, CONVERT(char(10), O.OrderDate, 101) AS 'MM/DD/YYYY Order Date'
	, C.CompanyName
	, P.ProductName 
	, Cat.CategoryName
	, OD.Quantity	
FROM northwind.dbo.[Order Details] AS OD
	INNER JOIN northwind.dbo.Orders AS O 
		ON OD.OrderID = O.OrderID
	INNER JOIN northwind.dbo.Customers AS C 
		ON C.CustomerID = O.CustomerID
	INNER JOIN northwind.dbo.Products AS P 
		ON P.ProductID = OD.ProductID
	INNER JOIN northwind.dbo.Categories AS Cat 
		ON Cat.CategoryID = P.CategoryID
ORDER BY OD.ProductID
COMPUTE sum(OD.Quantity) BY OD.ProductID
COMPUTE sum(OD.Quantity)