create table tb(ID int,BID varchar(20),ISMust varchar(10),Result varchar(10))
insert into tb select 1,'0','true','OK'
insert into tb select 2,'1','true','NO'
insert into tb select 3,'1,2','true',null
insert into tb select 4,'2,3','true',null
go
declare @sql varchar(2000)
select @sql='select * from tb where id in('+bid+')' from tb
exec(@sql)
/*
ID          BID                  ISMust     Result
----------- -------------------- ---------- ----------
2           1                    true       NO
3           1,2                  true       NULL

(2 行受影响)

*/
go
drop table tb

------解决方案--------------------
SQL code
----------------------------
-- Author  :fredrickhu(小F，向高手学习)
-- Date    :2011-09-21 09:58:52
-- Verstion:
--      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,[BID] varchar(3),[ISMust] varchar(4),[Result] varchar(2))
insert [tb]
select 1,'0','true','OK' union all
select 2,'1','true','NO' union all
select 3,'1,2','true',null union all
select 4,'2,3','true',null
--------------开始查询--------------------------
select distinct a.* from tb a,tb b where CHARINDEX(','+ltrim(b.ID)+',',','+a.BID+',')>0  and a.ID<>4
----------------结果----------------------------
/* ID          BID  ISMust Result
----------- ---- ------ ------
2           1    true   NO
3           1,2  true   NULL

(2 行受影响)
*/