USE ReportServer
GO
DECLARE @NotUsedDays INT
SELECT @NotUsedDays = 30
SELECT Name,Path,LastUsedDate,NotUsedsince=DATEDIFF(DD,LastUsedDate,GETDATE())
FROM dbo.catalog C
JOIN (
SELECT ReportID,LastUsedDate= MAX(timestart)
FROM dbo.executionlog
GROUP BY ReportID
) E
ON C.ItemID = E.ReportID
WHERE DATEDIFF(DD,LastUsedDate,GETDATE()) >= @NotUsedDays
ORDER BY NotUsedsince ASC