Web Listing 2: Table Expression to Group Results by Employee
WITH C AS
(
  SELECT CustomerID, EmployeeID
  FROM dbo.Orders
  WHERE OrderDate >= '19960101' AND OrderDate < '19970101'

  INTERSECT

  SELECT CustomerID, EmployeeID
  FROM dbo.Orders
  WHERE OrderDate >= '19970101' AND OrderDate < '19980101'
)
SELECT EmployeeID, COUNT(*) AS NumCusts
FROM C
GROUP BY EmployeeID;