SQL Server 2008 R2 - Рекурсивный SQL - возможно ли это?

Question

У меня есть следующая таблица:

| Article-Material1 | Article-Material2 | 
|-------------------|-------------------| 
| article001  | article002  | 
| article001  | article003  | 
| article001  | material001  | 
| material001  |     | 
| article002  | article004  | 
| article002  | material002  | 
| material002  |     | 
| article003  | material003  | 
| material003  |     | 
| article004  | material004  | 
| material004  |     | 
| article005  | article010  | 
| article005  | article011  | 
| article005  | material001  | 
| article010  | material005  | 
| material005  |     | 
| article011  | article012  | 
| article011  | material004  | 
| article011  | material006  | 
| material006  |     | 
| article012  | material002  | 
| article012  | material007  | 
| material007  |     | 

И я хочу, чтобы достичь подобный вывод:

article001 
    |- article002 
     |- article004 
      |- material004 
     |- material002 
    |- article003 
     |- material003 
    |- material001 
article005 
    |- article010 
     |- material005 
    |- article011 
     |- article012 
      |- material002 
      |- material007 
     |- material004 
     |- material006 
    |- material001 

Я понятия не имею, если это возможно с помощью SQL. Если это невозможно, что еще я могу попытаться получить в правильном направлении?

Answer 1

Declare @YourTable table ([Article-Material1] varchar(25),[Article-Material2] varchar(25)) 
Insert Into @YourTable values 
('article001','article002'), 
('article001','article003'), 
('article001','material001'), 
('material001',null), 
('article002','article004'), 
('article002','material002'), 
('material002',null), 
('article003','material003'), 
('material003',null), 
('article004','material004'), 
('material004',null), 
('article005','article010'), 
('article005','article011'), 
('article005','material001'), 
('article010','material005'), 
('material005',null), 
('article011','article012'), 
('article011','material004'), 
('article011','material006'), 
('material006',null), 
('article012','material002'), 
('article012','material007'), 
('material007',null) 


Declare @Top varchar(25) = null  --<< Sets top of Hier Try 'article002' 
Declare @Nest varchar(25) = '|-----' --<< Optional: Added for readability 

;with cte0 as (
     Select ID=[Article-Material2] 
      ,Pt=[Article-Material1] 
     From @YourTable 
     Where [Article-Material2] is not null 
     Union All 
     Select ID=[Article-Material1] 
      ,Pt=null 
     From @YourTable 
     Where [Article-Material1] not in (Select [Article-Material2] from @YourTable where [Article-Material2] is not null))    
,  cteP as (
     Select Distinct 
      Seq = cast(ID as varchar(500)) 
      ,ID 
      ,Pt 
      ,Lvl=1 
     From cte0 
     Where IsNull(@Top,'X') = case when @Top is null then isnull(Pt,'X') else ID end 
     Union All 
     Select Seq = cast(p.Seq+'.'+r.ID+r.Pt as varchar(500)) 
      ,r.ID 
      ,r.Pt 
      ,p.Lvl+1 
     From cte0 r 
     Join cteP p on r.Pt = p.ID and r.Pt=p.ID) 
    ,cteR1 as (Select *,R1=Row_Number() over (Order By Seq) From cteP) 
    ,cteR2 as (Select A.Seq,A.ID,R2=Max(B.R1) From cteR1 A Join cteR1 B on (B.Seq like A.Seq+'%') Group By A.Seq,A.ID) 
Select Distinct 
     A.R1 
     ,B.R2 
     ,A.ID 
     ,A.Pt 
     ,A.Lvl 
     ,Title = Replicate(@Nest,A.Lvl-1) + A.ID 
From cteR1 A 
Join cteR2 B on A.Seq=B.Seq where R2>=R1 
Order By A.R1 

Возвращает

Теперь, просто для удовольствия, установите @top к «article002» и вы получите:

Answer 2

Для целей презентации вы можете использовать следующий код на основании предыдущего сообщения.
SQL Challenge/Puzzle: How to create an ASCII art hierarchy tree with an SQL query?

with  h (id,pid) 
      as 
      (
       select  [Article-Material2] as id 
          ,[Article-Material1] as pid 

       from  mytable 

       where  [Article-Material2] is not null 

       union all 

       select  distinct 
          [Article-Material1]  as id 
          ,null     as pid 

       from  mytable 

       where  [Article-Material1] not in (select [Article-Material2] from mytable where [Article-Material2] is not null) 
      )  

      ,last_sibling (id) 
      as 
      (
       select  max (id) 
       from  h 
       group by pid 
      ) 

      ,tree (id,branch,path) 
      as 
      (
       select  h.id 
          ,cast ('' as varchar(max)) 
          ,cast (h.id as varchar(max)) 

       from  h 

       where  h.pid is null 

       union all 

       select  h.id 
          ,t.branch + case when (select 1 from last_sibling ls where ls.id = t.id) = 1 then ' ' else '|' end + ' ' 
          ,t.path + '_' + h.id 

       from     tree   t 

          join  h 

          on   h.pid = 
             t.id 
      ) 

      ,vertical_space (n) 
      as 
      (
       select  1 

       union all 

       select  vs.n + 1 
       from  vertical_space vs 
       where  vs.n < 2 
      ) 

select  t.branch + case vs.n when 1 then '|____' + ' ' + t.id else '|' end 

from     tree   t 

      cross join vertical_space vs 

order by t.path 
      ,vs.n desc 

option  (maxrecursion 0) 
; 

---

| 
|____ article001 
| | 
| |____ article002 
| | | 
| | |____ article004 
| | | | 
| | | |____ material004 
| | | 
| | |____ material002 
| | 
| |____ article003 
| | | 
| | |____ material003 
| | 
| |____ material001 
| 
|____ article005 
    | 
    |____ article010 
    | | 
    | |____ material005 
    | 
    |____ article011 
    | | 
    | |____ article012 
    | | | 
    | | |____ material002 
    | | | 
    | | |____ material007 
    | | 
    | |____ material004 
    | | 
    | |____ material006 
    | 
    |____ material001