Flatten recursive data - tsql

Question

I have a table glclassifications (Exact software) that looks like this:
CREATE TABLE [glclassifications](
[ID] [nvarchar](500) NULL, --(contains uniqueidentifier)
[Code] [nvarchar](500) NULL,
[Description] [nvarchar](500) NULL,
[Parent] [nvarchar](500) NULL --(contains uniqueidentifier)
)
It holds classifications that are hierarchical (hence the Parent column that refers to the ID of another record.)
I need this table to be 'flattened' so that I have
Parent_ID,
Parent_code,
Parent_description,
--child1
Child1_ID,
Child1_code,
Child1_description,
--child2
Child2_ID....
-- up until including child9
and so on.
My predecessor left me with this query that violates a lot of the designprinciples that we agreed upon. One of those is not using (temp)tables. I would like to simplify this script and preferably get the output as a view and not as a table. A catch is that the resulting view needs to deliver columns for 8 children, even if there are less in the table...
/* drop duplicates in glclassifications */
WITH CTE AS (
SELECT ROW_NUMBER() OVER (
PARTITION BY ID
ORDER BY ( SELECT 0)
) RN
FROM [dbo].[glclassifications]
)
DELETE FROM CTE
WHERE RN > 1;
/* drop tmp table */
DROP TABLE IF EXISTS #H;
CREATE TABLE #H (
Code varchar(100),
Description varchar(250),
ID varchar(100),
Division int
)
/* declare table */
DECLARE #n INT = 1
DECLARE #Sql varchar(50)
WHILE #n < 10 BEGIN
DECLARE #col_name varchar(10) = CONCAT('Code_' , #n)
SET #Sql = 'ALTER TABLE #H ADD ' + QUOTENAME(#col_name) + ' varchar(20) NULL'
EXEC (#Sql)
SET #col_name = CONCAT('Name_' , #n)
SET #Sql = 'ALTER TABLE #H ADD ' + QUOTENAME(#col_name) + ' varchar(250) NULL'
EXEC (#Sql)
SET #n = #n + 1
END
/* insert level 1 */
INSERT INTO #H (Code,[Description],ID,Division,Code_1, Name_1)
SELECT
Code,Description,ID,bip_office,Code,Description
FROM
[dbo].[glclassifications]
WHERE Parent = ''
/* insert level 2 */
INSERT INTO #H (Code,[Description],ID,Division,Code_1, Name_1, Code_2, Name_2)
SELECT
e.Code,e.Description,e.Id,e.bip_office,Code_1,Name_1,e.Code,e.Description
FROM
[dbo].[glclassifications] e
JOIN #H h on h.ID = e.Parent
WHERE e.ID not in (SELECT DISTINCT ID from #H ) AND Parent IS NOT NULL ;
/* insert level 3 */
INSERT INTO #H (Code,[Description],ID,Division,Code_1, Name_1, Code_2, Name_2,Code_3, Name_3)
SELECT
e.Code,e.Description,e.Id,e.bip_office, Code_1,Name_1,Code_2, Name_2,e.Code,e.Description
FROM
[dbo].[glclassifications] e
JOIN #H h on h.ID = e.Parent
WHERE e.ID not in (SELECT DISTINCT ID from #H ) AND Parent IS NOT NULL ;
/* insert level 4 */
INSERT INTO #H (Code,[Description],ID,Division,Code_1, Name_1, Code_2, Name_2,Code_3, Name_3, Code_4, Name_4)
SELECT
e.Code,e.Description,e.Id,e.bip_office, Code_1,Name_1,Code_2, Name_2,Code_3, Name_3,e.Code,e.Description
FROM
[dbo].[glclassifications] e
JOIN #H h on h.ID = e.Parent
WHERE e.ID not in (SELECT DISTINCT ID from #H ) AND Parent IS NOT NULL ;
/* insert level 5 */
INSERT INTO #H (Code,[Description],ID,Division,Code_1, Name_1, Code_2, Name_2,Code_3, Name_3, Code_4, Name_4, Code_5, Name_5)
SELECT
e.Code,e.Description,e.Id,e.bip_office,Code_1,Name_1,Code_2, Name_2,Code_3, Name_3,Code_4, Name_4,e.Code,e.Description
FROM
[dbo].[glclassifications] e
JOIN #H h on h.ID = e.Parent
WHERE e.ID not in (SELECT DISTINCT ID from #H ) AND Parent IS NOT NULL ;
/* insert level 6 */
INSERT INTO #H (Code,[Description],ID,Division,Code_1, Name_1, Code_2, Name_2,Code_3, Name_3, Code_4, Name_4, Code_5, Name_5,Code_6, Name_6)
SELECT
e.Code,e.Description,e.Id,e.bip_office,Code_1,Name_1,Code_2, Name_2,Code_3, Name_3,Code_4, Name_4,Code_5, Name_5,e.Code,e.Description
FROM
[dbo].[glclassifications] e
JOIN #H h on h.ID = e.Parent
WHERE e.ID not in (SELECT DISTINCT ID from #H ) AND Parent IS NOT NULL ;
/* insert level 7 */
INSERT INTO #H (Code,[Description],ID,Division,Code_1, Name_1, Code_2, Name_2,Code_3, Name_3, Code_4, Name_4, Code_5, Name_5,Code_6, Name_6,Code_7, Name_8)
SELECT
e.Code,e.Description,e.Id,e.bip_office,Code_1,Name_1,Code_2, Name_2,Code_3, Name_3,Code_4, Name_4,Code_5, Name_5,Code_6, Name_6,e.Code,e.Description
FROM
[dbo].[glclassifications] e
JOIN #H h on h.ID = e.Parent
WHERE e.ID not in (SELECT DISTINCT ID from #H ) AND Parent IS NOT NULL;
/* store to table */
DROP TABLE IF EXISTS [dbo].[gb-hierarchie];
SELECT hie.*
INTO [dbo].[gb-hierarchie]
FROM #H hie
I did this
WITH cte_org AS (
SELECT
ID,
Code,
Description,
Parent
FROM
[dbo].[glclassifications]
WHERE len(parent) = 0
UNION ALL
SELECT
e.ID,
e.Code,
e.Description,
e.parent
FROM
[dbo].[glclassifications] e
INNER JOIN cte_org o
ON o.ID = e.parent
)
SELECT * FROM cte_org;
but how to continue?

Answer 1

With thanks to Bill Jetzer: simply joining the tables on itself 8 times was the easiest way to get these results