Select * From 表A Where .....

Select ItemName From 表B Where plan_id=@plan_id 

Select * From 表A 

Select * From 表A Where ID IN (Select ItemName From 表B Where plan_id=@plan_id )

Select ItemName From 表B Where plan_id=@plan_id
if (@@rowcount = 1) and (ItemName   =   'xx')
    Select * From 表A
else
    Select * From 表A Where ID IN (Select ItemName From 表B Where plan_id=@plan_id )

------解决方案--------------------
SQL code
drop table tb
create table tb (id int,AN varchar(8000),CN varchar(8000))
insert tb select 1,'a','121'
insert tb select 2,'','123'
insert tb select 3,'s','123'

create table tb (id int,AN varchar(8000),CN varchar(8000))
insert tb select 1,'a','121'
insert tb select 2,'','123'
if(exists(select 1 from tb where an != '' and cn='123') ) 
exec('select * from tb where an !='''' and cn =''123''')
else
exec('select * from tb where an ='''' and cn =''123''')

------解决方案--------------------
使用
if else
SQL code

declare @ID int
set @ID = 1
if @ID = 1
begin
select COunt(*) from  sysobjects
set @ID = 2
end
else
select count(*) from sysfiles

------解决方案--------------------
if @@rowcount = 1 and Case_ItemID = 'All'
????????????????////////
郁闷，怎么能这样用的
----------------
SQL code

declare @DisplayChar int
declare @Plan_ID int
declare @Case_ItemID varchar(20)
set @Plan_ID  ='1006'
Select @Case_ItemID = Ltrim(Case_ItemID) 
From Report_Planparameter2 
      Where Plan_Id =@Plan_ID  and Case_name = 'account'
if @@rowcount = 1 and @Case_ItemID = 'All'
   select @DisplayChar = ''
else
   select @DisplayChar = '1'