tree, Sql Server - rextester

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CREATE FUNCTION [dbo].[SplitString] (@Text varchar(max),@Delimiter varchar(10))
    Returns Table 
    As
    Return (  
	   Select Pos = Row_Number() over (Order By (Select null))
		    ,Value = LTrim(RTrim(B.i.value('(./text())[1]', 'varchar(max)')))
	   From (Select x = Cast('<x>'+ Replace(@Text,@Delimiter,'</x><x>')+'</x>' as xml).query('.')) as A 
	   Cross Apply x.nodes('x') AS B(i)
    );
    
    GO 
    
    DECLARE @SampleData TABLE
    (
	   NAMEHID varchar(30)
    )

INSERT INTO @SampleData
    (
	   NAMEHID
    )
    VALUES
    ('/2/8/5/'),('/5/11/12/'),('/8/7/9/')

;with temp AS
    (
	   SELECT * FROM @SampleData sd
	   CROSS APPLY
	   (
		  SELECT * FROM [dbo].[SplitString](STUFF(LEFT(sd.NameHID,LEN(sd.NameHID) - 1),1,1,''),'/')
	   ) cr
    )
    ,cte AS
    (
	   SELECT t.NameHID, t.[Value] , 0 AS Lvl FROM temp t
	   WHERE t.Pos = 1
	   AND NOT EXISTS (	
				    SELECT * FROM temp t2 
				    WHERE  t2.[Value] = t.[Value] AND t2.Pos > 1
				   )  -- root ID
	   UNION ALL

SELECT t2.NameHID, t2.[Value], cte.Lvl + 1 
	   FROM  cte 
	   INNER JOIN temp t ON cte.[Value] = t.[Value] AND t.Pos = 1
	   INNER JOIN temp t2 ON t.NameHID = t2.NameHID AND t2.Pos > 1
    )
    SELECT cte.[Value] AS NameId, cte.Lvl 
    FROM cte 
    ORDER BY cte.Lvl, cte.[Value]
    OPTION(MAXRECURSION 0)

View schema
Execution time: 0,09 sec, rows selected: 7, rows affected: 3, absolute service time: 0,22 sec