SQL Query: Count Replies for Active Feedback with NULL Handling

SELECT T., ISNULL(T.ReplyNum, 0) AS ReplyNum FROM ( SELECT A., ROW_NUMBER() OVER (ORDER BY A.ID) AS RowNum, (SELECT COUNT(1) FROM ActiveReply C WHERE C.FeedbackID = A.ID GROUP BY C.FeedbackID) AS ReplyNum FROM [ActiveFeedback] A LEFT JOIN ActiveReply B ON A.ID = B.FeedbackID GROUP BY B.FeedbackID, A.ID, A.[ActiveID], A.[UserID], A.[UserName], A.[Content], A.[CreateTime] ) AS T