Hi try something similar to this:

CREATE PROC [dbo].[parListClubs] -- Parameter list

AS

SELECT

-1 AS ClubID,

' ' AS ClubName

UNION ALL

SELECT

Entity_ID AS ClubID,

Name AS ClubName

FROM dbo.Clubs

ORDER BY ClubName

--This will be your detailed extraction --

CREATE PROC [dbo].[rptClubMembershipType] (@ClubID VARCHAR(100) = -1)

AS

SELECT

MT.Description AS [Membership Type],

COUNT(*) AS #

FROM

dbo.MembershipType MT

LEFT JOIN

dbo.Members_Cycling MC

ON MT.ID = MC.Cycling_Province_MembershipType

LEFT JOIN

Members M

ON MC.Entity_ID = M.Entity_ID

WHERE

((NULLIF(@ClubID,-1) IS NULL) OR (M.ClubID IN (@ClubID)))

GROUP BY

MT.Description

Hope this helps: Give care to the where clause!

if u r not expecting nulls in ur filter column u can use

FilterColumn in (isnull(nullif(@Parameter,-1),FilterColumn))