with t as
(select row_number() over(order by TopFlag desc,IssueTime desc) rn,* 
from nInfoMain)
select * 
from t 
where rn in ([指定的rn]-1,[指定的rn]+1)

------解决方案--------------------
SQL code

declare @rid int

select *,rid=identity(int,1,1)
  into #tb
from nInfoMain 
order by TopFlag desc,IssueTime desc

select @rid = rid from #tb where --你查询哪条数据的条件

select *
from #tb
where rid between @rid-1 and @rid+1

------解决方案--------------------
SQL code
----------------------------
-- Author  :fredrickhu(小F，向高手学习)
-- Date    :2011-11-24 11:36:15
-- Version:
--      Microsoft SQL Server 2008 R2 (RTM) - 10.50.1617.0 (Intel X86) 
--    Apr 22 2011 11:57:00 
--    Copyright (c) Microsoft Corporation
--    Enterprise Evaluation Edition on Windows NT 6.1 <X64> (Build 7600: ) (WOW64)
--
----------------------------
--> 测试数据：[tb]
if object_id('[tb]') is not null drop table [tb]
go 
create table [tb]([ID] int,[text] varchar(4),[TopFlag] int,[time] datetime)
insert [tb]
select 280,'内容',1,'2011-04-07 11:03:05' union all
select 164,'内容',1,'2011-03-07 11:03:05' union all
select 583,'内容',0,'2011-11-05 11:03:05' union all
select 251,'内容',0,'2011-06-11 11:03:05' union all
select 283,'内容',0,'2011-04-05 11:03:05' union all
select 211,'内容',0,'2011-03-24 11:03:05'
--------------开始查询--------------------------
declare @id int
set @id=164
;with f as
(
select px=ROW_NUMBER()over(order by getdate()),* from tb
)
select ID,TEXT,topflag,time  from  f where px=(select px from f where ID=@id)-1
union all 
select ID,TEXT,topflag,time  from  f where px=(select px from f where ID=@id)+1
----------------结果----------------------------
/* ID          TEXT topflag     time
----------- ---- ----------- -----------------------
280         内容   1           2011-04-07 11:03:05.000
583         内容   0           2011-11-05 11:03:05.000

(2 行受影响)

*/