Using CASE in WHERE Statement when parameter has multiple values

Question

I have a problem which I think relates to having a multiple value parameter.

In my TblActivity there are two fields TblActivity.ActivityServActId

Answer 1

So after a lot of messing around I put together a simple workaround for this by dropping my use of CASE altogether - but I have a suspicion that this is not a terribly efficient way of doing things.

WHERE
(@YESNOActivity = 'No' OR (@YESNOActivity = 'Yes' AND
TblActivity.ActivityServActId IN (@ServiceActivity)))

AND

(@YESNOContract = 'No' OR (@YESNOContract = 'Yes' AND
TblActivity.ActivityContractId IN (@Contract)))