If exists(select * from sysobjects where 
id=object_id(N'[dbo].[T_Test]') and xtype = 'u')
DROP Table T_Test
go

CREATE Table T_Test (
f_idint IDENTITY(1, 1) Primary Key,
f_charChar(8) default '',
f_varchar　 varchar(8) default '',
f_nvarchar　 nvarchar(8) default '',
f_datetime　 datetime default getdate(),
f_intint default 0,
f_bigint　 bigint default 0,
f_decimal　 decimal(18, 6) default 0.00,
f_number　 numeric(18, 6) default 0.00,
f_floatfloat default 0.00
)
go

INSERT INTO T_Test (f_char) values('001')
INSERT INTO T_Test (f_char) values('002')
go

If exists(select * from sysobjects 
where id=object_id(N'[dbo].[Tri_Test_Upd]') 
and objectproperty(id,N'istrigger')=1)
DROP TRIGGER Tri_Test_Upd
go

CREATE TRIGGER Tri_Test_Upd ON T_Test --WITH ENCRYPTION
FOR UPDATE
AS
DECLARE @iRowCnt INT

SET @iRowCnt = @@rowcount

IF @iRowCnt < 1
 RETURN

DECLARE
　@sTable　VARCHAR(128),
　@sPKName VARCHAR(32),
　@sColName VARCHAR(128)

DECLARE
　@iColCnt　INT,
　@iColId　INT

DECLARE
　@iTINYINT,
　@jTINYINT,
　@iSegment TINYINT,
　@iVal　 TINYINT,
　@iLog2　TINYINT

DECLARE
　@sSQL　VARCHAR(8000)

SET @sTable = 't_test'
SET @sPKName = 'f_id'

-- 求得当前表列个数
SELECT @iColCnt = Count(1) FROM syscolumns WHERE id = object_id(@sTable)

-- 以8 个字段为一小段
SET @iSegment = CASE
　 WHEN @iColCnt / 8 = @iColCnt / 8.0
THEN
 @iColCnt / 8
ELSE
 @iColCnt / 8 + 1
END
-- 将数据存入 临时表
SELECT * INTO #Inserted FROM Inserted
SELECT * INTO #Deleted FROM Deleted

-- 中间处理数据用
CREATE TABLE #Temp(
f_PKVal　varchar(254) not null primary key,
f_OldVal　varchar(254),
f_NewVal　varchar(254)
)

SET @i = 0

WHILE @i < @iSegment
 BEGIN
 IF @iColCnt < 9
　SET @iVal= COLUMNS_UPDATED() 
 ELSE
　SET @iVal= SubString(COLUMNS_UPDATED(), @i + 1, 1)

 -- 等于0, 则表示当前小节所对应的8个字段无一被改.
 IF @iVal = 0
　BEGIN
　SET @i = @i + 1
　CONTINUE
　END

 WHILE @iVal > 0
　BEGIN
　SET @j = 0
　SET @iLog2 = @iVal / 2

　WHILE @iLog2 > 0
　 BEGIN
　 SET @j = @j + 1
　 SET @iLog2 = @iLog2 / 2
　 END

　-- 得到被Update 的 列ID
　SET @iColId = 8 * @i + @j + 1

　-- 将Update列名 赋予 @sColName
　SELECT @sColName = S.name 
　 FROM Inserted as I,
 Deleted as D,
 Syscolumns as S
　WHERE I.F_id = D.F_id
　 AND S.id = object_id(@sTable)
　 AND S.colid = @iColId

　Truncate table #Temp
　-- 拼成动态语句
　SET @sSQL = 'INSERT INTO #Temp (f_PkVal, f_OldVal, f_NewVal) ' + 
　 'SELECT Convert( varchar(200), I.' + @sPkName + '), ' + 
　 'Convert( varchar(200), D.' + @sColName + '), ' + 
　 'Convert( varchar(200), I.' + @sColName + ') ' + 
 'FROM　#Inserted as I, #Deleted as D ' +
 'WHERE I.' + @sPKName + ' = D.' + @sPKName + 
 ' AND I.' + @sColName + ' <> D.' + @sColName

　EXEC(@sSQL)

　-- 测试输出
　 Select f_pkVal,　@sColName as f_column_name, f_oldVal, f_newVal　FROM #temp
　-- 实际上用 将信息处理后插入消息表
　/*
　.....
　
　INSERT INTO T_Message(....)
　 SELECT 要组织的内容
FROM #temp
　*/

　SET @iVal = @iVal - Power(2, @j)
　END

 SET @i = @i + 1
 END

DROP TABLE #Inserted
DROP TABLE #Deleted
DROP TABLE #Temp

go

Update T_test Set f_datetime = getdate(), 
f_float = 0.0123, f_int= 1

--　上面Update 语句共修改了三个列
--　实际输出
1.)
1 f_int 0 1
2 f_int 0 1
2.)
1 f_datetime May 15 2004　5:30PM May 15 2004　5:31PM
2 f_datetime May 15 2004　5:30PM May 15 2004　5:31PM
3.)
1 f_float 0 0.0123
2 f_float 0 0.0123

1,@iVal = 1 = 2^(1-1);
2,@iVal =　2 = 2^(2-1);
3,@iVal =　4 = 2^(3-1);
4,@iVal =　8 = 2^(4-11);
5,@iVal =　16 = 2^(5-1);
6,@iVal =　32 = 2^(6-1);
7,@iVal =　64 = 2^(7-1);
8,@iVal =　128 = 2^(8-1);

@iVal = 2^(1-1) + 2^(2-1) = 3;

@iVal = 2^(2-1) + 2^(5-1) + 2^(8-1) = 146;
...

@iVal = 2^(1-1) + 2^(2-1) + ... + 2^(8-1) = 255;