SQL Server 2008中的CTE：如何递归计算小计

我有一张桌子，其中汽车的某些零件与层次结构相关，而且我还要花每一行制造这些零件的成本。这是表的简化：

I've got a table where some parts of a car are related hierarchically and I also have the cost of manufacturing those parts in each one of the rows. This is a simplification of the table:

parentId  Id description qty manufacturingCost costDescripcion
-------- --- ----------- --- ----------------- ---------------
NULL      1  Car          1  100               Assembly the car
NULL      2  Motorcycle   1  100               Assembly the motrocycle
 1       11  Wheel        4   20               Assembly the wheel
11      111  Rim          1   50               Manufacture the rim
11      112  Tire         1   60               Manufacture the tire
 1       12  Door+Window  4   30               Assembly the door and the window
12      121  Door         1   30               Manufacture the door
12      122  Window       2   10               Manufacture the window
 2       11  Wheel        2   15               Assembly the wheel

我需要让整个家谱开始在汽车中显示总数量和总费用ts每个分支。更好地解释：一辆汽车有4个轮子，每个轮子有1个轮辋和1个轮胎，所以我应该得到1个汽车，4个轮子，4个轮胎，4个轮辋。成本稍微复杂一点：组装汽车的成本为100美元，但我必须增加这一成本，即组装4个车轮（4x20）和制造4个轮圈（4x50）和4个轮胎的成本（4x60），门和窗户也一样。

I need to get the whole family tree starting in 'Car' and showing the total quantities and the total costs for each branch. Better explained: a car has 4 wheels and each wheel has 1 rim and 1 tire, so I should get 1 Car, 4 Wheels, 4 Tires, 4 Rims. A little bit more complicated for the costs: Assembling a car costs 100$, but I have to add to this cost, the one of assembling the 4 wheels (4x20) and the cost of manufacturing the 4 rims (4x50) and the 4 tires (4x60), and the same for the doors and windows.

这是预期的结果：

parentId  Id description qty manufacturingCost   recLevel
-------- --- ----------- --- -----------------   ---------------
NULL       1  Car          1 940 (100+4*130+4*80) 0
 1        11  Wheel        4 130 (20+50+60)       1
 1        12  Door+Window  4 80  (30+30+2*10)     1
12       121  Door         4 30                   2
12       122  Window       8 10                   2
11       111  Rim          4 50                   2
11       112  Tire         4 60                   2

我可以使用递归函数或存储过程轻松实现这一目标，但是使用更多函数却很慢复杂的结构，因此我尝试使用通用表表达式来实现。但是我没有找到合计费用的方法。我使用的是递归CTE，从最高层开始，一直到下降，我得到了数量的总和，但是我应该从结构的内部到外部进行总和，我该怎么做？

I can easily reach this one using a recursive Function or Stored Procedure but it is very slow with more complex structures, so I am trying to do it using Common Table Expressions. But I didn´t find the way to sum the costs. I use a recursive CTE starting in the top level and going down and I get the sum of the quantities, but I should go from inside to outside in the structure to sum the costs, how can I do that?

这是创建表的代码：

CREATE TABLE #Costs 
(
  parentId int, 
  Id int, 
  description varchar(50),
  qty int, 
  manufacturingCost int,
  costDescripcion varchar(150)
)

INSERT INTO #Costs VALUES (NULL , 1, 'Car', 1, 100, 'Assembly the car')
INSERT INTO #Costs VALUES (NULL , 2, 'Motorcycle', 1, 100, 'Assembly the motrocycle')
INSERT INTO #Costs VALUES (1 , 11, 'Wheel', 4, 20, 'Assembly the wheel')
INSERT INTO #Costs VALUES (11 , 111, 'Rim', 1, 50, 'Manufacture the rim')
INSERT INTO #Costs VALUES (11 , 112, 'Tire', 1, 60, 'Manufacture the tire')
INSERT INTO #Costs VALUES (1 , 12, 'Door+Window', 4, 30, 'Assembly the door and the window')
INSERT INTO #Costs VALUES (12 , 121, 'Door', 1, 30, 'Manufacture the door')
INSERT INTO #Costs VALUES (12 , 122, 'Window', 2, 10, 'Manufacture the window')
INSERT INTO #Costs VALUES (2 , 11, 'Wheel', 2, 15, 'Assembly the wheel')

这是我写的CTE：

with CTE(parentId, id, description, totalQty, manufacturingCost, recLevel)
as
(
  select c.parentId, c.id, c.description, c.qty, c.manufacturingCost, 0
  from #Costs c
  where c.id = 1

  union all

  select c.parentId, c.id, c.description, c.qty * ct.totalQty, c.manufacturingCost, ct.recLevel + 1
  from #Costs c
  inner join CTE ct on ct.id = c.parentId 
)
select * from CTE

这是我得到的结果，如您所见，不是预期的结果（未添加成本）：

And this is the result I get that, as you can see, is not the expected one (the costs are not being added):

parentId  Id description qty manufacturingCost recLevel
-------- --- ----------- --- ----------------- ---------------
NULL       1  Car          1 100                0
 1        11  Wheel        4 20                 1
 1        12  Door+Window  4 30                 1
12       121  Door         4 30                 2
12       122  Window       8 10                 2
11       111  Rim          4 50                 2
11       112  Tire         4 60                 2

是否可以做我想使用的东西CTE？如果是这样，我该怎么办？

Is it possible to do what I want using CTE? If so, how can I do it?

非常感谢

安东