SELECT DISTINCT ISNULL(cap.title, '') AS Captitle, ISNULL(cap.title, 'NULL') AS CaptitleDesc, cha.title AS Expr1
FROM           ABC
WHERE        (chap.title = @ChapPARAM)

SELECT DISTINCT chap.title, cap.title AS Expr1, cap.ed_pecent
FROM            ABC
WHERE        (chap.title = @ChapPARAM) AND (ISNULL(cap.title, '') IN (@CapPARAM))
ORDER BY chap.title