求一条sql语句，请帮忙

[gsk99]

我希望查询一些数据，要求是这样的：
我查询的条件是根据日期（DTime）及类型（Type）来查询的，表名为XX
类型Type包括A和B
我希望查询到的结果是：
当DTime=查询时间时，我对于Type没有要求，即查出这天Type为A和B的所有数据，对于DTime<查询时间时，我希望查出所有Type为B的的数据，A的数据不显示。我希望用一条Sql语句来实现

换个说法：我希望查询小于等于<='2006-01-31'的数据，对于时间='2006-01-31'的数据，我要查询的Type没有限制，但是对于时间<'2006-01-31'的数据，我只要查询出Type为B的数据。

请高手指点

[Snoworld]

SELECT * FROM TB WHERE DTIME<'2006-01-31' AND TYPE='B'
UNION
SELECT * FROM TB WHERE DTIME='2006-01-31'

[hellowork]

----创建测试数据
declare @xx table(dtime datetime,type varchar(10))
insert @xx
select '2006-01-31','A' union all
select '2006-01-31','B' union all
select '2006-01-30','A' union all
select '2006-01-30','B' union all
select '2006-01-30','A' union all
select '2006-01-30','B'
----查询
declare @dt datetime
set @dt = '2006-01-31'
select * from @xx where dtime < @dt
union all
select * from @xx where datediff(dd,dtime,@dt) = 0 and type = 'B'

[tianxingzh]

斯蒂芬

[gsk99]

declare @xx table(dtime datetime,type varchar(10))
insert @xx
select '2006-01-31','A' union all
select '2006-01-31','B' union all
select '2006-01-30','A' union all
select '2006-01-30','B' union all
select '2006-01-30','A' union all
select '2006-01-30','B' union all
select '2006-01-29','A' union all
select '2006-01-29','B' union all
select '2006-01-29','A' union all
select '2006-01-29','B'
----查询
declare @dt datetime
set @dt = '2006-01-31'
select * from @xx where dtime < @dt and type = 'B'
union all
select * from @xx where datediff(dd,dtime,@dt) = 0