LISTING 4: Three Simple Queries in Northwind

-- No UDF
SELECT 
	top 100
	OrderId
	,CustomerId
FROM
	orders



-- With the UDF DoAlmostNothing()
SELECT 
	top 100
	OrderId
	,CustomerId
	,dbo.DoAlmostNothing()
FROM
	orders



-- With the UDF PerformHeavyIO()
SELECT 
	top 100
	OrderId
	,CustomerId
	,dbo.PerformHeavyIO()
FROM
	orders