I don't think you can do that. But lets say you have Category1, Category2, Category3.
Now, you don't know what category the user will select , or if he will select all of them. So you do like this :
CREATE PROCEDURE pSearchRecords
(
@SearchCategory1 varchar(50),
@SearchCategory2 varchar(50),
@SearchCategory3 varchar(50)
)
AS
SELECT * FROM tAddressBook
WHERE (Category1 IS NULL OR Category1 = @SearchCategory1)
AND (Category2 IS NULL OR Category2 = @SearchCategory2) -- if Category2 will be null, it will be ignored.
AND (Category3 IS NULL OR Category3 = @SearchCategory3)
That's one way of doing it ... maybe there are other