存储过程为参数NULL时的处理方法

SELECT [Projname],[version],[state] FROM [dbo].[Goods] WHERE 
[Projname] = CASE WHEN @Projname IS NULL THEN [Projname] ELSE @Projname END

或者

SELECT [Projname],[version],[state] FROM [dbo].[Goods] WHERE 
（[Projname] = @Projname OR @Projname IS NULL ）