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)))

Answer 2

If your @ServiceActivity is something like 1,2,3

You can do something like this

WHERE  `,1,2,3,` LIKE `%,1,%` 

So you format your variables

WHERE  ',' + @ServiceActivity + ',' LIKE '%,' + ID + ',%'

SQL FIDDLE DEMO

SELECT *
FROM 
    (SELECT '1,2,3,4' as X UNION ALL
     SELECT '2,3,4,5' as X UNION ALL
     SELECT '3,4,5,6' as X UNION ALL
     SELECT '1,3,4,5' as X 
     ) as T
WHERE ',' + X + ','  LIKE  '%,1,%'

For Your Case

(CASE WHEN @YESNOActivity = 'Yes' 
           THEN ',' + @ServiceActivity + ','
           ELSE NULL 
 END)
LIKE
(CASE WHEN @YESNOActivity = 'Yes' 
           THEN '%,' + TblActivity.ActivityServActId + ',%'
           ELSE 0 
 END) 

Answer 3

In SQL, the IN clause does not support parameters the way you are using them. The general syntax is

IN (1, 2, 3, 4)

you have

IN (@Param)

where something like @Param = '1, 2, 3, 4'

Internally, SQL will turn this into

IN ('1, 2, 3, 4')

Note the quotes... you are now matching against a string!

There are a number of ways to address this. Search SO for "sql in clause parameter", pick one that works for you, and upvote it.

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(Added)

Parameterize an SQL IN clause seems pretty definitive on the subject. While long ago I upvoted the third reply (the one with table-value parameters), any of the high-vote answers could do the trick. The ideal answer depends on the overall problem you are working with. (I am not familiar with SSRS, and can't give more specific advice.)