(select top 3 *
from 表A a
inner join 表B b on a.id=b.aid
where a.cid in (10000)
order by b.id desc)
union all
(select top 3 *
from 表A a
inner join 表B b on a.id=b.aid
where a.cid in (10001)
order by b.id desc)
union all
(select top 3 *
from 表A a
inner join 表B b on a.id=b.aid
where a.cid in (10002)
order by b.id desc)

------解决方案--------------------
SQL code
--得到每组前几条数据
--假設每組Col1中， Col3不會重復

--建立測試環境
Create Table TEST
(Col1 Varchar(10),
 Col2 Varchar(10),
 Col3 Int)
--插入數據
Insert TEST Select 'BD1V','Label', 4
Union All Select 'BD1V', 'BATT', 2
Union All Select 'BD1V', 'ODD', 3
Union All Select 'BD1V', 'HDD', 5
Union All Select 'BD1V', 'LCD', 1
Union All Select 'BD1W','HDD', 3
Union All Select 'BD1W','RAM', 8
Union All Select 'BD1W','TP CABLE', 5
Union All Select 'BD1W','LCD', 6
Union All Select 'BD1W','Label', 2
Union All Select 'BL3', 'LCD CABLE', 7
Union All Select 'BL3', 'LABEL', 6
Union All Select 'BL3', 'LCD', 5
Union All Select 'BL3', 'RAM', 1
Union All Select 'BL3D', 'Label', 4
GO
--測試
--方法一：
Select Col1, Col2, Col3 From TEST A
Where (Select Count(*) From TEST Where Col1 = A.Col1 And Col3 > A.Col3) < 3
Order By Col1, Col3 Desc
--方法二：
Select Col1, Col2, Col3 From TEST A
Where Exists (Select Count(*) From TEST Where Col1 = A.Col1 And Col3 > A.Col3 Having Count(*) < 3)
Order By Col1, Col3 Desc
--方法三：
Select Col1, Col2, Col3 From TEST A
Where Col3 In (Select TOP 3 Col3 From TEST Where Col1 = A.Col1 Order By Col3 Desc)
Order By Col1, Col3 Desc
GO
--刪除測試環境
Drop Table TEST
--結果
/*
Col1  Col2   Col3
BD1V HDD  5
BD1V Label  4
BD1V ODD  3
BD1W RAM  8
BD1W LCD   6
BD1W TP CABLE 5
BL3  LCD CABLE 7
BL3  LABEL  6
BL3  LCD   5
BL3D Label  4
*/

------解决方案--------------------
SQL code
--如果是查询：
select a.* , t.* from a , b t
where a.id = t.aid and t.id in (select top 3 id from b where aid = t.aid order by id)

select a.* , t.* from a , b t
where a.id = t.aid and t.id in (select top 3 id from b where aid = t.aid order by id desc)