IF EXISTS (SELECT 1 FROM SYSOBJECTS WHERE name = 'tba')
BEGIN
    DROP TABLE tba
END
GO
CREATE TABLE tba
(
    Field1 INT,
    Field2 INT,
    Field3 INT
)
GO
INSERT INTO tba
SELECT 1, 2, 3 UNION
SELECT 4, 5, 6 
GO

SELECT * FROM tba
WHERE    (CHARINDEX(',' + RTRIM(7) + ',',',' + RTRIM(Field1) + ',' + RTRIM(Field2) + ',' + RTRIM(Field3) + ',') + 
        CHARINDEX(',' + RTRIM(1) + ',',',' + RTRIM(Field1) + ',' + RTRIM(Field2) + ',' + RTRIM(Field3) + ',') + 
        CHARINDEX(',' + RTRIM(8) + ',',',' + RTRIM(Field1) + ',' + RTRIM(Field2) + ',' + RTRIM(Field3) + ',')) > 0

------解决方案--------------------
SQL code
----------------------------
-- Author  :fredrickhu(小F，向高手学习)
-- Date    :2012-07-18 13:15:36
-- Version:
--      Microsoft SQL Server 2008 R2 (RTM) - 10.50.1617.0 (Intel X86) 
--    Apr 22 2011 11:57:00 
--    Copyright (c) Microsoft Corporation
--    Enterprise 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]([Field1] int,[Field2] int,[Field3] int)
insert [tb]
select 1,2,3 union all
select 4,5,6
--------------开始查询--------------------------
declare @Field1 int,@Field2 int ,@Field3 int 
set @Field1=7
set @Field2=1
set @Field3=8
select * from tb where checksum(@field1,@field2,@Field3) in (select checksum(field1,field2,Field3) from tb)
----------------结果----------------------------
/* Field1      Field2      Field3
----------- ----------- -----------

(0 行受影响)
*/

------解决方案--------------------
insert into tb(Field1,Field2,Field3)  
select @Field1,@Field2,@Field3  
where not exists (select null from tb where  
Field1 = @Field1 and Field2 =@Field2 and Field3 = @Field3)  

不知道和4楼的比较起来哪个效率会高点。