C# WinApp ช่วยแปลง SQL นี้ให้อยู่ในรูปแบบ IIF(ISNULL(column),0,column) หน่อยครับ

 SELECT tblProductType.pdtID, tblProductType.Barcode, tblProductType.ProductType_1,
 (iif(isnull( (SELECT sum( tblProductReceive.Count) from tblProductReceive where tblProductReceive.pdtID = tblProductType.pdtID  )),0, (SELECT sum( tblProductReceive.Count) from tblProductReceive where tblProductReceive.pdtID = tblProductType.pdtID  )) ) AS sumR,
 (iif(isnull((SELECT sum(  tblProductSale.Count) from tblProductSale where tblProductSale.pdtID = tblProductType.pdtID  )),0,(SELECT sum(  tblProductSale.Count) from tblProductSale where tblProductSale.pdtID = tblProductType.pdtID  ))) AS sumS,
 (sumR-sumS) AS sumC
FROM tblProductType;

SELECT p.pdtID, p.Barcode, p.ProductType,
sum(isnull(r.Count,0)) as SumR,
sum(isnull(S.Count,0)) as SumS,
sum(isnull(r.Count,0))-sum(isnull(S.Count,0)) as SumC
from tblProductType p
left join tblProductReceive r on p.pdtID =r.pdtID 
left join tblProductSale s on p.pdtID  = s.pdtID 

SELECT t.*, ISNULL(t.sumR,0)-ISNULL(t.sumS,0) As sumC
FROM (SELECT p.pdtID, p.Barcode, p.ProductType_1,
 (SELECT sum(x.Count) from tblProductReceive As x where x.pdtID = p.pdtID  ) AS sumR,
 (SELECT sum(x.Count) from tblProductSale As x where x.pdtID = p.pdtID  ) AS sumS,
 (sumR-sumS) AS sumC
FROM tblProductType As p) As t;