跪求一条SQL命令.蛮复杂的.该怎么解决

跪求一条SQL命令....蛮复杂的..
表：
AddDate Class
2009-10-30 02:00:00 新闻
2009-10-29 02:00:00 新闻
2009-10-28 02:00:00 新闻
2009-10-20 02:00:00 娱乐
2009-10-29 02:00:00 情感


得出：
栏目几天未更新!（也就是取各栏目最大的时间 和 当前时间做比较得出结果）

预想结果：
栏目 未更新时间（单位：天）
娱乐 13
情感 4
新闻 3



[解决办法]

SQL code

--> 测试数据：[TB]if object_id('[TB]') is not null drop table [TB]create table [TB]([AddDate] datetime,[Class] varchar(4))insert [TB]select '2009-10-30 02:00:00','新闻' union allselect '2009-10-29 02:00:00','新闻' union allselect '2009-10-28 02:00:00','新闻' union allselect '2009-10-20 02:00:00','娱乐' union allselect '2009-10-29 02:00:00','情感'SELECT     Class,    MAX(DATEDIFF(DD,AddDate,GETDATE()))AS [时间] FROM     TB GROUP BY     Class ORDER BY     [时间] DESC（所影响的行数为 5 行）Class 时间          ----- ----------- 娱乐    13新闻    5情感    4（所影响的行数为 3 行）
[解决办法]
SQL code
if object_id('[TB]') is not null drop table [TB]create table [TB]([AddDate] datetime,[Class] varchar(4))insert [TB]select '2009-10-30 02:00:00','新闻' union allselect '2009-10-29 02:00:00','新闻' union allselect '2009-10-28 02:00:00','新闻' union allselect '2009-10-20 02:00:00','娱乐' union allselect '2009-10-29 02:00:00','情感'select datediff(day,max([AddDate]),getdate()) as  '未更新时间',[Class] from [TB] group by [Class]未更新时间       Class----------- -----4           情感3           新闻13          娱乐(3 行受影响)
[解决办法]
SQL code
------------------------------ Author  :fredrickhu(我是小F，向高手学习)-- Date    :2009-11-02 09:01:55-- Version:--      Microsoft SQL Server 2005 - 9.00.4035.00 (Intel X86) --    Nov 24 2008 13:01:59 --    Copyright (c) 1988-2005 Microsoft Corporation--    Developer Edition on Windows NT 5.2 (Build 3790: Service Pack 1)--------------------------------> 测试数据：[tb]if object_id('[tb]') is not null drop table [tb]go create table [tb]([AddDate] datetime,[Class] varchar(4))insert [tb]select '2009-10-30 02:00:00','新闻' union allselect '2009-10-29 02:00:00','新闻' union allselect '2009-10-28 02:00:00','新闻' union allselect '2009-10-20 02:00:00','娱乐' union allselect '2009-10-29 02:00:00','情感'--------------开始查询--------------------------select  [Class] as 栏目,   datediff(day,max([AddDate]),getdate()) as  未更新时间from   [TB] group by   [Class]----------------结果----------------------------/* 栏目   未更新时间---- -----------情感   4新闻   3娱乐   13(3 行受影响)*/
[解决办法]
SQL code
------------------------------ Author  :fredrickhu(我是小F，向高手学习)-- Date    :2009-11-02 09:01:55-- Version:--      Microsoft SQL Server 2005 - 9.00.4035.00 (Intel X86) --    Nov 24 2008 13:01:59 --    Copyright (c) 1988-2005 Microsoft Corporation--    Developer Edition on Windows NT 5.2 (Build 3790: Service Pack 1)--------------------------------> 测试数据：[tb]if object_id('[tb]') is not null drop table [tb]go create table [tb]([AddDate] datetime,[Class] varchar(4))insert [tb]select '2009-10-30 02:00:00','新闻' union allselect '2009-10-29 02:00:00','新闻' union allselect '2009-10-28 02:00:00','新闻' union allselect '2009-10-20 02:00:00','娱乐' union allselect '2009-10-29 02:00:00','情感'--------------开始查询--------------------------select  [Class] as 栏目,   datediff(day,[AddDate],getdate()) as  未更新时间from   [TB] twhere   not exists(select 1 from tb where Class=t.Class and AddDate>t.AddDate)----------------结果----------------------------/* 栏目   未更新时间---- -----------情感   4新闻   3娱乐   13(3 行受影响)*/