SQL Server 2008中的CTE：如何递归计算小计 [英] CTE in SQL Server 2008: how to calculate subtotals recursively
问题描述
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
推荐答案
您可以尝试这样的事情
DECLARE @Table TABLE(
parentId INT,
Id INT,
description VARCHAR(50),
qty FLOAT,
manufacturingCost FLOAT,
costDescripcion VARCHAR(50)
)
INSERT INTO @Table SELECT NULL,1,'Car',1,100,'Assembly the car'
INSERT INTO @Table SELECT NULL,2,'Motorcycle',1,100,'Assembly the motrocycle'
INSERT INTO @Table SELECT 1,11,'Wheel',4,20,'Assembly the wheel'
INSERT INTO @Table SELECT 11,111,'Rim',1,50,'Manufacture the rim'
INSERT INTO @Table SELECT 11,112,'Tire',1,60,'Manufacture the tire'
INSERT INTO @Table SELECT 1,12,'Door+Window',4,30,'Assembly the door and the window'
INSERT INTO @Table SELECT 12,121,'Door',1,30,'Manufacture the door'
INSERT INTO @Table SELECT 12,122,'Window',2,10,'Manufacture the window'
INSERT INTO @Table SELECT 2,11,'Wheel',2,15,'Assembly the wheel'
;WITH Vals AS (
SELECT *,
qty Level_Qty,
CAST(id AS VARCHAR(MAX)) + '\' AS [LEVEL]
FROM @Table
WHERE parentId IS NULL
UNION ALL
SELECT t.*,
p.qty * t.qty Level_Qty,
CAST(p.[LEVEL] AS VARCHAR(MAX)) + CAST(t.id AS VARCHAR(MAX)) + '\' AS [LEVEL]
FROM @Table t INNER JOIN
Vals p ON p.Id = t.parentId
)
SELECT *,
(SELECT SUM(Level_Qty * manufacturingCost) FROM Vals WHERE [Level] LIKE v.[LEVEL] + '%') / Level_Qty
FROM Vals v
ORDER BY [LEVEL]
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