从具有级别路径的表生成父子层次结构 [英] Generate a parent-child hierarchy from table with levels paths

问题描述

我设法在这样的表中转换了一些不可读的数据.SQL 表表示多父平面层次结构.问题是，如何生成正常的参差不齐的 sql parent-child 层次结构:ID |元素 |父基于下面附加的级别和结构?

I managed to transform some unreadable data in such a table. The SQL table represents a multipleparent flat hierarchy. The question is, how can I generate a normal ragged sql parent-child hierarchy: ID | Element | Parent based on the levels and the structure attached below ?

推荐答案

您可以创建一个具有层次结构和自动递增 ID 的新表，如下所示:

You could create a new table with the hierarchical structure, and an auto incrementing ID, like this:

create table hierarchy (
  id int not null identity (1,1) primary key,
  element varchar(100),
  parent int
);

然后您首先要向其中添加 1 级元素，因为它们没有父元素:

Then you would first add the level 1 elements to it, as they have no parent:

insert into hierarchy (element, parent)
  select     distinct f.level1, null
  from       flat f;

由于您现在为这些元素生成了 id 值，您可以添加下一个级别，如下所示:

As you now have the id values generated for these elements, you can add the next level, like this:

insert into hierarchy (element, parent)
  select     distinct f.level2, h1.id
  from       hierarchy h1
  inner join flat f
          on f.level1 = h1.element
  where      h1.parent is null;

您可以将这种模式重复到下一个级别:

This pattern you can repeat to the next levels:

insert into hierarchy (element, parent)
  select     distinct f.level3, h2.id
  from       hierarchy h1
  inner join hierarchy h2
          on h2.parent = h1.id
  inner join flat f
          on f.level1 = h1.element
         and f.level2 = h2.element
  where      h1.parent is null;

insert into hierarchy (element, parent)
  select     distinct f.level4, h3.id
  from       hierarchy h1
  inner join hierarchy h2
          on h2.parent = h1.id
  inner join hierarchy h3
          on h3.parent = h2.id
  inner join flat f
          on f.level1 = h1.element
         and f.level2 = h2.element
         and f.level3 = h3.element
  where      h1.parent is null;

insert into hierarchy (element, parent)
  select     distinct f.level5, h3.id
  from       hierarchy h1
  inner join hierarchy h2
          on h2.parent = h1.id
  inner join hierarchy h3
          on h3.parent = h2.id
  inner join hierarchy h4
          on h4.parent = h3.id
  inner join flat f
          on f.level1 = h1.element
         and f.level2 = h2.element
         and f.level3 = h3.element
         and f.level4 = h4.element
  where      h1.parent is null;

insert into hierarchy (element, parent)
  select     distinct f.level6, h3.id
  from       hierarchy h1
  inner join hierarchy h2
          on h2.parent = h1.id
  inner join hierarchy h3
          on h3.parent = h2.id
  inner join hierarchy h4
          on h4.parent = h3.id
  inner join hierarchy h5
          on h5.parent = h4.id
  inner join flat f
          on f.level1 = h1.element
         and f.level2 = h2.element
         and f.level3 = h3.element
         and f.level4 = h4.element
         and f.level5 = h5.element
  where      h1.parent is null;

...等，根据需要深入到各个级别.

... etc, as far into the levels as needed.

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