在sqlserver 中用一條語句實現 如果為空白顯示全部資料

--產生測試資料if not object_id('Tempdb..T_20081010') is null    drop table T_20081010GoCreate table T_20081010([ID] int,[S_ID] nvarchar(1),[P_ID] nvarchar(10))Insert T_20081010select 1,'a','2009-02-00' union allselect 2,'a','2009-02-28' union allselect 3,'b','2009-01-28' union allselect 4,'b','2009-01-25' union allselect 5,'b','2009-02-27' union allselect 6,'b','2009-02-26'Go--Select * from T_20081010 

--實現：declare @P int set @P=''select * from T_20081010where (case  when (id=@p) then  1  when @p='' then 1  else 0 end)=1