Printing tree with SQL CTE
The schema is as follows:
CREATE TABLE [Structure](
[StructureId] [uniqueidentifier] NOT NULL,
[SequenceNumber] [int] NOT NULL, -- order for siblings, unique per parent
[ParentStructureId] [uniqueidentifier] NULL,
CONSTRAINT [Structure_PK] PRIMARY KEY CLUSTERED
(
[StructureId] ASC
)
) ON [PRIMARY]
ALTER TABLE [Structure] WITH CHECK ADD CONSTRAINT [Structure_FK1]
FOREIGN KEY([ParentStructureId])
REFERENCES [Structure] ([StructureId])
Currently, I can get all the logical data out with the follow CTE, but I would like to print it directly in a depth first fashion.
WITH SCTE (StructureId, Level, Seq, ParentId)
AS
(
SELECT StructureId, 0, SequenceNumber, [ParentStructureId]
FROM Structure
WHERE [ParentStructureId] IS NULL
AND StructureId = 'F6C5F016-1270-47C1-972F-349C32DFC92A'
UNION ALL
SELECT Structure.StructureId, Level + 1, SequenceNumber, ParentStructureId
FROM Structure
INNER JOIN SCTE ON SCTE.StructureId = Structure.ParentStructureId
)
SELECT * FROM SCTE
ORDER BY Level, ParentId, Seq
The output is as follows (truncated here):
StructureId Level Seq ParentId
F6C5F016-1270-47C1-972F-349C32DFC92A 0 0 NULL
D2E34429-401A-4A49-9E18-E81CCA0FB417 1 0 F6C5F016-1270-47C1-972F-349C32DFC92A
0CC5E16C-9194-40CA-9F72-1CED2972D7CA 1 1 F6C5F016-1270-47C1-972F-349C32DFC92A
1ECD1D30-EB85-42B0-969F-75794343E3B4 1 2 F6C5F016-1270-47C1-972F-349C32DFC92A
EEC3A981-B790-4600-8CD1-F15972CD9230 2 0 0CC5E16C-9194-40CA-9F72-1CED2972D7CA
4406F639-2F58-4918-A9EF-A4B0F379BEA0 2 1 0CC5E16C-9194-40CA-9F72-1CED2972D7CA
FCAF7870-C606-4AA6-85EE-57B90B1B0CC3 2 2 0CC5E16C-9194-40CA-9F72-1CED2972D7CA
855DF5FB-1593-4E5B-8EF9-3770B45F89D6 2 3 0CC5E16C-9194-40CA-9F72-1CED2972D7CA
3D16DF32-C04F-49B4-B0D9-5BDC9104F810 2 4 0CC5E16C-9194-40CA-9F72-1CED2972D7CA
A1084D00-0198-47D9-87E0-BB8234233F14 2 5 0CC5E16C-9194-40CA-9F72-1CED2972D7CA
CE443C0D-376F-46EC-9914-32C6B7200DB1 2 6 0CC5E16C-9194-40CA-9F72-1CED2972D7CA
0DEA587D-4FCF-414C-AD71-FB00829F8082 2 7 0CC5E16C-9194-40CA-9F72-1CED2972D7CA
CC9FC8D3-254A-486B-8DC4-07E57627476C 2 0 1ECD1D30-EB85-42B0-969F-75794343E3B4
215565CC-501F-4850-B8AE-5466DA5E6854 2 1 1ECD1D30-EB85-42B0-969F-75794343E3B4
D4E6C8E5-5ADD-4AD1-B59B-1A672F66888A 2 2 1ECD1D30-EB85-42B0-969F-75794343E3B4
796C65BF-4714-4DBF-A97A-2150DBE3098C 2 3 1ECD1D30-EB85-42B0-969F-75794343E3B4
B39DEB9C-BE42-43B4-9C38-968399D7D1E2 2 4 1ECD1D30-EB85-42B0-969F-75794343E3B4
6C2F70C6-1DA0-4E1A-BBC1-D7FCAFE6AFEE 2 0 D2E34429-401A-4A49-9E18-E81CCA0FB417
75D7B43B-C971-46B4-BC42-58C3605ADD79 2 1 D2E34429-401A-4A49-9E18-E81CCA0FB417
0B5AAAA0-A69F-431E-86BA-148444D7B1E6 2 2 D2E34429-401A-4A49-9E18-E81CCA0FB417
CB3CF66B-D83A-45E2-953A-6F0CEE094F5B 2 3 D2E34429-401A-4A49-9E18-E81CCA0FB417
1D5F69C3-F036-4667-BD75-A0DC1506DB6D 2 4 D2E34429-401A-4A49-9E18-E81CCA0FB417
71B894F7-B9FC-44DE-AEDB-E6FA026A6082 2 5 D2E34429-401A-4A49-9E18-E81CCA0FB417
F1DFA1E1-013B-449C-9D9D-14C64E75D418 2 6 D2E34429-401A-4A49-9E18-E81CCA0FB417
As you can see, the result is 'breadth first' which makes printing a tree kinda impossible as it is now.
Is there any way (there probably is a trivial way, but my SQL skills are extremely poor) to get the resultant list in 'tree printing friendly' format?
I know I could just dump the results into a pro开发者_C百科gram and code the output, but as an exercise I would prefer doing this in SQL itself.
Thanks
Edited after comment. You could add the path to a node, and order on that:
declare @t table (id int, parent int)
insert @t (id, parent) values (1, null), (2,1), (3,2), (4,3), (5,null), (6,5)
; with cte as (
select id, parent
, cast(RIGHT(REPLICATE('0',12) +
CONVERT(varchar(12),id),12) as varchar(max)) Path
from @t
where parent is null
union all
select child.id, child.parent
, parent.Path + RIGHT(REPLICATE('0',12) +
CONVERT(varchar(12),child.id),12) as Path
from @t child
join cte parent
on parent.id = child.parent
)
select *
from cte
order by
Path
This prints the root first, followed by leaves in order. If your id can be larger than 12 digits, increase the number in the char(x)
casts.
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