SQL ต้องการใช้ตำสั่ง GROUP BY ใน Procedure ที่มีอยู่แล้ว

USE [TM_ERP]
GO
/****** Object:  StoredProcedure [dbo].[MyProcedure]    Script Date: 6/14/2018 9:27:14 AM ******/
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
-- =============================================
-- Author:		<Author,,Name>
-- Create date: <Create Date,,>
-- Description:	<Description,,>
-- =============================================
ALTER PROCEDURE [dbo].[MyProcedure]
	-- Add the parameters for the stored procedure here
	@StartDate			datetime,
	@ToDate				datetime,
	@FromSupplierCode	nvarchar(20),
	@ToSupplierCode		nvarchar(20),
	@OtherSideStatus	bit,
	@SideCode			nvarchar(10),
	@SupplierType		nvarchar(1)
AS
BEGIN
		IF @OtherSideStatus = 0
			BEGIN
				IF @SideCode IS NULL
					BEGIN
						SELECT sa.PoNo,
							   po.SupplierID,
							   (SELECT sup.SupplierName FROM 
							   [dbo].[Suppliers] sup WHERE sup.SupplierID=po.SupplierID) 
							   AS SupplierName,
							   sa.SupplierType,
							   sa.SupplierAssessSubjectID,
							   sa.Grade
							   

						FROM [dbo].[SupplierAssess] sa INNER JOIN
							 [dbo].[PurchaseOrders] po ON sa.PoNo = po.PoNo
							 
							 

						WHERE(po.SupplierID BETWEEN @FromSupplierCode AND @ToSupplierCode) AND
							 (sa.Grade = '5' OR sa.Grade = '4' OR sa.Grade = '3' OR sa.Grade = '2' OR sa.Grade = '1') AND
							 (sa.GrDocumentDate BETWEEN @StartDate AND @ToDate) AND
							 (po.SupplierAssessStatus = 1)AND
							 po.DocumentType =  'A' AND
							 sa.SupplierType = @SupplierType
						ORDER BY po.SupplierID,po.PoNo,sa.SupplierAssessSubjectID
					END
				ELSE
					BEGIN
						SELECT sa.PoNo,
							   po.SupplierID,
							   (SELECT sup.SupplierName FROM 
							   [dbo].[Suppliers] sup WHERE sup.SupplierID=po.SupplierID) 
							   AS SupplierName,
							   sa.SupplierType,
							   sa.SupplierAssessSubjectID,
							   sa.Grade
						FROM [dbo].[SupplierAssess] sa INNER JOIN
							 [dbo].[PurchaseOrders] po ON sa.PoNo = po.PoNo
						WHERE(po.SupplierID BETWEEN @FromSupplierCode AND @ToSupplierCode)AND
							 (sa.Grade = '5' OR sa.Grade = '4' OR sa.Grade = '3' OR sa.Grade = '2' OR sa.Grade = '1') AND
							 (sa.GrDocumentDate BETWEEN @StartDate AND @ToDate) AND
							 (po.SupplierAssessStatus = 1)AND
							 po.DocumentType = 'A' AND
							 po.SideID=@SideCode AND
							 sa.SupplierType = @SupplierType
						ORDER BY po.SupplierID,po.PoNo,sa.SupplierAssessSubjectID

					END
				END
			ELSE
				BEGIN
					IF @SideCode IS NULL
						BEGIN
						SELECT sa.PoNo,
							   po.SupplierID,
							   (SELECT sup.SupplierName FROM 
							   [dbo].[Suppliers] sup WHERE sup.SupplierID=po.SupplierID) 
							   AS SupplierName,
							   sa.SupplierType,
							   sa.SupplierAssessSubjectID,
							   sa.Grade
						FROM [dbo].[SupplierAssess] sa INNER JOIN
							 [dbo].[PurchaseOrders] po ON sa.PoNo = po.PoNo
						WHERE(po.SupplierID BETWEEN @FromSupplierCode AND @ToSupplierCode)AND
							 (sa.Grade = '5' OR sa.Grade = '4' OR sa.Grade = '3' OR sa.Grade = '2' OR sa.Grade = '1') AND
							 (sa.GrDocumentDate BETWEEN @StartDate AND @ToDate) AND
							 (po.SupplierAssessStatus = 1)AND
							 po.DocumentType = 'B' OR po.DocumentType = 'C' AND
							 sa.SupplierType = @SupplierType
						ORDER BY po.SupplierID,po.PoNo,sa.SupplierAssessSubjectID

					END
				ELSE
					BEGIN
						SELECT sa.PoNo,
							   po.SupplierID,
							   (SELECT sup.SupplierName FROM 
							   [dbo].[Suppliers] sup WHERE sup.SupplierID=po.SupplierID) 
							   AS SupplierName,
							   sa.SupplierType,
							   sa.SupplierAssessSubjectID,
							   sa.Grade
						FROM [dbo].[SupplierAssess] sa INNER JOIN
							 [dbo].[PurchaseOrders] po ON sa.PoNo = po.PoNo
						WHERE(po.SupplierID BETWEEN @FromSupplierCode AND @ToSupplierCode)AND
							 (sa.Grade = '5' OR sa.Grade = '4' OR sa.Grade = '3' OR sa.Grade = '2' OR sa.Grade = '1') AND
							 (sa.GrDocumentDate BETWEEN @StartDate AND @ToDate) AND
							 (po.SupplierAssessStatus = 1)AND
							  po.DocumentType = 'B' OR po.DocumentType = 'C' AND
							 po.SideID=@SideCode AND
							 sa.SupplierType = @SupplierType
						ORDER BY po.SupplierID,po.PoNo,sa.SupplierAssessSubjectID

					END	 
			END
		END

SELECT sa.Grade, COUNT(*)
	FROM SupplierAssess sa INNER JOIN PurchaseOrders po 
	ON sa.PoNo = po.PoNo INNER JOIN Suppliers sup
	ON sup.SupplierID = po.SupplierID
	WHERE sup.SupplierID = 'SUP-000016' and (sa.Grade ='5' or sa.Grade = '4' or sa.Grade = '3' or sa.Grade = '2' or sa.Grade = '1')
GROUP BY sa.Grade