T-SQL中存储过程输出参数的默认值有何用？

/****** Object:  StoredProcedure [dbo].[test]    Script Date: 06/16/2009 14:16:26 ******/
IF  EXISTS (SELECT * FROM sys.objects WHERE object_id = OBJECT_ID(N'[dbo].[test]') AND type in (N'P', N'PC'))
DROP PROCEDURE [dbo].[test]
go

create proc test
(@In int=0,
@Out  int=0 output)
as
begin
 --set @Out=@In+1
 select @Out
end

go

declare @Test int

exec test @Out=@Test output

select @Test

 

该例子中输出参数@Out的默认值0似乎根本没有起作用。

 

采用一下方式可以输出参数默认值

IF  EXISTS (SELECT * FROM sys.objects WHERE object_id = OBJECT_ID(N'[dbo].[test]') AND type in (N'P', N'PC'))
DROP PROCEDURE [dbo].[test]
go
create proc test
(@In int=0,
@Out  int=250 output)
as
begin
--set @Out=@In+1
select @Out
end
go

exec test

 

但问题是如果我们不用select @Out输出@Out，该参数的默认值又如何获取呢？