Store Procedure傳入的參數若不是全部有傳則Where條件的寫法

gistfile1.txt

ALTER PROCEDURE [ERP].[usp_GetProjectSummaryData] 
@ProjectCategoryID UniqueIdentifier Null
,@ProjectID UniqueIdentifier Null
AS
BEGIN
-- SET NOCOUNT ON added to prevent extra result sets from
-- interfering with SELECT statements.
SET NOCOUNT ON;
Select *
From Project P
Where ProjectCategoryID = isnull(@ProjectCategoryID,ProjectCategoryID) 
      And ProjectID = isnull(@ProjectID,ProjectID) 
END