Tree data to flat data in SQL Server - sql-server

Question

I am facing the problem tree view to flat view, I have some data that has come from a tree, those are stored in a table that is presenting in my picture below left. I am saying the top level of tree is level1, and second level is level2 and so on. My expected result that is representing in my picture below right.
How can I convert my data to my expected result dynamically in SQL Server? We have to create dynamic column level1, level2, level3 and so on. Do you have any idea? Thanks.
Here is the sample data
IF OBJECT_ID('tempdb..#TestData', 'U') IS NOT NULL
DROP TABLE #TestData;
CREATE TABLE #TestData (
Id INT NOT NULL,
SomeName VARCHAR(3) NOT NULL,
ParentId INT NULL
);
INSERT #TestData (Id, SomeName, ParentId) VALUES
(1, 'O', NULL),
(2, 'D1', 1),
(3, 'D2', 1),
(4, 'S1', 2),
(5, 'S2', 2),
(6, 'S1', 3),
(7, 'SP1', 3);
SELECT * FROM #TestData td;

Answer 1

You can query as below:
;With Cte as ( --Recursive CTE for traversing tree
Select *, convert(varchar(max),[name]) as NameLevel, 1 as Levl from #TreeData where ParentId is Null
Union all
Select t.Id, t.[Name], t.[ParentId], concat(c.NameLevel,',',t.[name]) as NameLevel, c.Levl + 1 as Levl from Cte c
inner join #TreeData t on c.Id = t.ParentId
)
Select * from (
select c.Id, c.Levl, a.[value]
,RowN = row_number() over(partition by Id order by Levl) from cte c
cross apply string_split(c.NameLevel,',') a
) sq
pivot(max([value]) for RowN in([1],[2],[3])) p --Pivot for getting all data
Output as below:
+---+------+------+----+
| 1 | 2 | 3 | Id |
+---+------+------+----+
| O | NULL | NULL | 1 |
| O | D1 | NULL | 2 |
| O | D2 | NULL | 3 |
| O | D1 | S1 | 4 |
| O | D1 | S2 | 5 |
| O | D2 | S1 | 6 |
| O | D2 | SP1 | 7 |
+---+------+------+----+
Below the input table and data I used:
Create Table #TreeData(Id int, [name] varchar(10), ParentId int)
Insert into #TreeData(id, [name], ParentId) values
(1,'O', null)
,(2,'D1', 1)
,(3,'D2', 1)
,(4,'S1', 2)
,(5,'S2', 2)
,(6,'S1', 3)
,(7,'SP1', 3)

Answer 2

IF OBJECT_ID('tempdb..#TreeData', 'U') IS NOT NULL
DROP TABLE #TreeData;
CREATE TABLE #TreeData (
Id INT NOT NULL,
SomeName VARCHAR(3) NOT NULL,
ParentId INT NULL
);
INSERT #TreeData (Id, SomeName, ParentId) VALUES
(1, 'O', NULL),
(2, 'D1', 1),
(3, 'D2', 1),
(4, 'S1', 2),
(5, 'S2', 2),
(6, 'S1', 3),
(7, 'SP1', 3);
--SELECT * FROM #TestData td;
;With Cte as ( --Recursive CTE for traversing tree
Select Id,SomeName,ParentId, convert(varchar(max),[SomeName]) as NameLevel, 1 as Levl from #TreeData where ParentId is Null
Union all
Select t.Id, t.[SomeName], t.[ParentId], (c.NameLevel +','+ t.[SomeName]) as NameLevel, c.Levl + convert(int, 1) as Levl
from Cte c
inner join #TreeData t on c.Id = t.ParentId
)
--select * from cte
Select * from (
select c.Id, c.Levl, a.Items
,RowN = row_number() over(partition by Id order by Levl) from cte c
cross apply split(c.NameLevel,',') a
) sq
pivot(max([Items]) for RowN in([1],[2],[3])) p --Pivot for getting all data

Answer 3

The following should give you the requested results.
Note: This solution relies on the use of an iTVF called tfn_Tally, I'll post the code for that below my answer.
IF OBJECT_ID('tempdb..#TestData', 'U') IS NOT NULL
DROP TABLE #TestData;
CREATE TABLE #TestData (
Id INT NOT NULL,
SomeName VARCHAR(3) NOT NULL,
ParentId INT NULL
);
INSERT #TestData (Id, SomeName, ParentId) VALUES
(1, 'O', NULL),
(2, 'D1', 1),
(3, 'D2', 1),
(4, 'S1', 2),
(5, 'S2', 2),
(6, 'S1', 3),
(7, 'SP1', 3);
-- SELECT * FROM #TestData td;
--===========================================
--===========================================
IF OBJECT_ID('tempdb..#RecursionResults', 'U') IS NOT NULL
DROP TABLE #RecursionResults;
WITH
cte_Recursion AS (
SELECT
td.Id,
SomeName = CAST(CAST(td.SomeName AS BINARY(5)) AS VARBINARY(1000)),
--td.ParentId,
NodeLevel = 1
FROM
#TestData td
WHERE
td.ParentId IS NULL
UNION ALL
SELECT
td.Id,
SomeName = CAST(CONCAT(r.SomeName, CAST(td.SomeName AS BINARY(5))) AS VARBINARY(1000)),
NodeLevel = r.NodeLevel + 1
FROM
cte_Recursion r
JOIN #TestData td
ON r.Id = td.ParentId
)
SELECT
Id = ISNULL(r.Id, 0), r.SomeName, r.NodeLevel
INTO #RecursionResults
FROM
cte_Recursion r;
-- adding a clustered index Id eliminates the sort operation on final select.
ALTER TABLE #RecursionResults ADD PRIMARY KEY CLUSTERED (Id);
-----------------------------------------
DECLARE
#PivotCount INT = (SELECT MAX(rr.NodeLevel) FROM #RecursionResults rr),
#PivotCols VARCHAR(1000) = '',
#PivotCAV VARCHAR(8000) = '',
#sql VARCHAR(8000),
#Debug BIT = 0; -- set to 0 to execute, 1 to DeBug.
SELECT TOP (#PivotCount)
#PivotCols = CONCAT(#PivotCols, CHAR(13), CHAR(10), CHAR(9), 'L', t.n, '.Level_', t.n, ','),
#PivotCAV = CONCAT(#PivotCAV, CHAR(13), CHAR(10), CHAR(9), 'CROSS APPLY ( VALUES (CAST(SUBSTRING(rr.SomeName,', (t.n - 1) * 5 + 1, ', ', 5, ') AS VARCHAR(5))) ) L', t.n, ' (Level_', t.n, ')'
)
FROM
dbo.tfn_Tally(#PivotCount, 1) t;
SET #sql = CONCAT('
SELECT ',
STUFF(#PivotCols, 1, 1, ''), '
rr.Id
FROM
#RecursionResults rr',
#PivotCAV, '
ORDER BY
rr.Id;');
IF #Debug = 1
BEGIN
PRINT(#sql);
END;
ELSE
BEGIN
EXEC (#sql);
END;
Function code for tfn_Tally...
CREATE FUNCTION dbo.tfn_Tally
/* ============================================================================
07/20/2017 JL, Created. Capable of creating a sequense of rows
ranging from -10,000,000,000,000,000 to 10,000,000,000,000,000
============================================================================ */
(
#NumOfRows BIGINT,
#StartWith BIGINT
)
RETURNS TABLE WITH SCHEMABINDING AS
RETURN
WITH
cte_n1 (n) AS (SELECT 1 FROM (VALUES (1),(1),(1),(1),(1),(1),(1),(1),(1),(1)) n (n)), -- 10 rows
cte_n2 (n) AS (SELECT 1 FROM cte_n1 a CROSS JOIN cte_n1 b), -- 100 rows
cte_n3 (n) AS (SELECT 1 FROM cte_n2 a CROSS JOIN cte_n2 b), -- 10,000 rows
cte_n4 (n) AS (SELECT 1 FROM cte_n3 a CROSS JOIN cte_n3 b), -- 100,000,000 rows
cte_Tally (n) AS (
SELECT TOP (#NumOfRows)
(ROW_NUMBER() OVER (ORDER BY (SELECT NULL)) - 1) + #StartWith
FROM
cte_n4 a CROSS JOIN cte_n4 b -- 10,000,000,000,000,000 rows
)
SELECT
t.n
FROM
cte_Tally t;
GO
HTH,
Jason