将父/子表转换为固定列的维表 [英] Transform a parent/child table to a fixed column dimentional table

问题描述

我有一个关系表(id，parentId，name)

I've a relational table (id, parentId, name)

我想将其转换为扁平的二维表

which I'd like to convert to a flattened dimentional table

(id，Level1，Level2，Level3，Level4)

(id, Level1, Level2, Level3, Level4)

我可以将深度固定为4深.

I'm ok fixing the depth at 4 deep.

我在递归CTE和数据透视方面取得了进步，但结果集不正确

I've made progress with a recursive CTE and pivot, but the result set isn't right

我知道

Id  Name   Level1 Level2
0   Root   NULL   NULL
1   NULL   L1     NULL

但我需要

Id  Name   Level1 Level2
0   Root   NULL   NULL
1   Root   L1     NULL

这是我要约会的

with rcte as
(
      select h.id
      ,h.parent_id
      ,h.name
      ,1 as HierarchyLevel 
  FROM RelTable h
  where id = 1
  union all
  select h2.id
       , h2.parent_id 
      , h2.name
      , r.HierarchyLevel + 1 AS HierarchyLevel 
  FROM RelTable h2
  inner join rcte r on h2.parent_id = r.id
 )
select id, parent_id, [1] as L1,[2] as L2,[3] as L3, [4] as L4
from (
select id,parent_id,name,HierarchyLevel from rcte
) as src
pivot  ( max(name)  for HierarchyLevel   in ([1],[2],[3],[4]) ) as pvt

我在做什么错了?

推荐答案

解决方案过于复杂?如果固定在四个深度，则可以通过一些简单的连接来完成...

Overcomplicating the solution? If it's fixed at four deep then it can be done with some simple joins...

SELECT
    L1.id as ID
    L1.Name as Level1
    L2.Name as Level2
    L3.Name as Level3
    L4.Name as Level4
FROM
    RelTable as L1

        INNER JOIN
    RelTable as L2
        ON L1.id = L2.ParentID

        INNER JOIN
    RelTable as L3
        ON L2.id = L3.ParentID

        INNER JOIN
    RelTable as L4
        ON L3.id = L4.ParentID

使用CTE的练习虽然没有用，但可以满足您的需要.

As an exercise in using CTEs its useless, but it does what you need.

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