Hierarchical data from the self-promotion table in the form of a tree

Question

It seems like this was asked and answered in all simple cases, except for the one I came across. I tried using recursive CTE to create this; maybe the cursor would be better? Or maybe a set of recursive functions will do the trick?

Can this be done in cte?

consider the following table

PrimaryKey   ParentKey  
1            NULL       
2            1       
3            6
4            7
5            2
6            1
7            NULL

should give

PK
1
-2
--5
-6
--3
7
-4

where the number of marks is equal to depth, my main difficulty is ordering.

Answer 1

This is kind of kludgey to do with an adjacency list scheme, but it can be done with a recursive CTE:

WITH Hierarchy AS
(
    SELECT
        PrimaryKey, ParentKey,
        CAST('/' + CAST(PrimaryKey AS varchar(10)) AS varchar(50)) AS [Path],
        CAST('' AS varchar(50)) AS Prefix
    FROM @Tbl
    WHERE ParentKey IS NULL

    UNION ALL

    SELECT
        t.PrimaryKey, t.ParentKey,
        CAST(h.[Path] + '/' + CAST(t.PrimaryKey AS varchar(10)) AS varchar(50)),
        CAST(h.Prefix + '-' AS varchar(50))
    FROM Hierarchy h
    INNER JOIN @Tbl t
        ON t.ParentKey = h.PrimaryKey
)
SELECT [Path], Prefix + CAST(PrimaryKey AS varchar(10)) AS Node
FROM Hierarchy
ORDER BY [Path]

, Prefix ( "" ) Path, .

Answer 2

- node, . str (x, 4) - 4 .

WITH TreePrinter(id, parent, path, prefix) AS
(
   SELECT 
      PrimaryKey, ParentKey, 
      CAST(str(PrimaryKey,4) AS varchar(max)),
      CAST('' AS varchar(max))
   FROM YourTable
   WHERE ParentKey IS NULL
   UNION ALL 
   SELECT child.PrimaryKey, child.ParentKey, 
     CAST(parent.path+'/'+STR(child.PrimaryKey,4) AS varchar(max)),
     CAST(parent.prefix+'-' AS varchar(max)),
     FROM YourTable parent
     INNER JOIN TreePrinter child ON child.id=parent.ParentKey
)
SELECT prefix+str(id) FROM TreePrinter
ORDER BY path