CTE 创建产品层次结构树

Question

我有以下三个 table 代表产品数据。简单说明一下，产品"A"和"B"是最终产品。为了找出构成产品 "A" 的部件，我们查看 "ProductComponents" table 给我们的 ComponentListId = 1.

根据 "PartsSubcomponents" table 查询此 ComponentListId 告诉我们它有两个子组件，即 A11 和 A12。

A11 很小，没有更多的子组件。但是，A12存在于"ProductComponents" table中，告诉我们它是用X1和X2制作的。

终端产品

EndProductId
A
B
...

产品组件

ProductId ComponentListId
A         1
A12       99
...

零件子组件

ComponentListId SubComponentId
1               A11
1               A12
99              X1
99              X2
...

我需要使用 CTE 来查找产品及其部件之间的层次结构级别。在这种情况下，结果应该是这样的：

EndProductId,ProductId,ComponentListId,SubcomponentId,Level
A,           A,        1,              A11,           L1
A,           A,        1,              A12,           L1
A,           A12,      99,             X1,            L2
A,           A12,      99,             X2,            L2

Answer 1

这是一个简单的递归 cte，它可以执行您想要的操作并产生您想要的输出：

CREATE TABLE #EndProducts
    (
      EndProductId NVARCHAR(1)
    );

INSERT  INTO #EndProducts
        ( EndProductId )
VALUES  ( 'A' ),
        ( 'B' );

CREATE TABLE #ProductComponents
    (
      ProductId NVARCHAR(3) ,
      ComponentListId INT
    );

INSERT  INTO #ProductComponents
        ( ProductId, ComponentListId )
VALUES  ( 'A', 1 ),
        ( 'A12', 99 );

CREATE TABLE #PartsSubcomponents
    (
      ComponentListId INT ,
      SubComponentId NVARCHAR(3)
    ); 

INSERT  INTO #PartsSubcomponents
        ( ComponentListId, SubComponentId )
VALUES  ( 1, 'A11' ),
        ( 1, 'A12' ),
        ( 99, 'X1' ),
        ( 99, 'X2' );

WITH    cte
          AS ( -- anchor member gets level 1
               SELECT   e.EndProductId ,
                        pc.ProductId ,
                        sc.ComponentListId ,
                        sc.SubComponentId ,
                        1 AS [Level]
               FROM     #EndProducts e
               INNER JOIN #ProductComponents pc 
                     ON e.EndProductId = pc.ProductId
               INNER JOIN #PartsSubcomponents sc 
                     ON pc.ComponentListId = sc.ComponentListId
               UNION ALL
               -- recursive member gets the additional data and increments levels
               SELECT   cte.EndProductId ,
                        cte.SubComponentId AS ProductId ,
                        pc.ComponentListId ,
                        sc.SubComponentId ,
                        cte.[Level] + 1 AS [Level]
               FROM     cte
               INNER JOIN #ProductComponents pc 
                     ON cte.SubComponentId = pc.ProductId
               INNER JOIN #PartsSubcomponents sc 
                     ON pc.ComponentListId = sc.ComponentListId
             )
    SELECT  *
    FROM    cte;

DROP TABLE #EndProducts;
DROP TABLE #PartsSubcomponents;
DROP TABLE #ProductComponents;

结果：

EndProductId    ProductId   ComponentListId SubComponentId  Level
A               A           1               A11             1
A               A           1               A12             1
A               A12         99              X1              2
A               A12         99              X2              2

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