Listing 2: Example of Putting Each Query in Its Own Stored Procedure
CREATE PROCEDURE NumberOfUsers
      @BeginDateTime DATETIME,
      @EndDateTime DATETIME,
      @MachineName VARCHAR(1000) = ''
AS
BEGIN

-- Calculate the number of users for the test.
   IF @MachineName = ''
         EXEC NumberOfUsersAll @BeginDateTime, @EndDateTime
   ELSE
         EXEC NumberOfUsersMachine @BeginDateTime, @EndDateTime, @MachineName

END

CREATE PROCEDURE NumberOfUsersAll
   @BeginDateTime DATETIME,
   @EndDateTime DATETIME
AS
BEGIN

-- Calculate the number of users for the test.
   SELECT COUNT(DISTINCT MachineName+UserName)
   FROM MetricEvent
   WHERE EndDateTime > @BeginDateTime
      AND EndDateTime < @EndDateTime

END

CREATE PROCEDURE NumberOfUsersMachine
    @BeginDateTime DATETIME,
    @EndDateTime DATETIME,
    @MachineName VARCHAR(1000) = ''
AS
BEGIN

-- Calculate the number of users for the test.
   SELECT COUNT(DISTINCT UserName)
   FROM MetricEvent
   WHERE EndDateTime > @BeginDateTime
      AND EndDateTime < @EndDateTime
      AND MachineName = @MachineName

END