Get hierarchical structure using SQL Server

Question

I have a self-referencing table with a primary key, id and a foreign key parent_id.

+------------+--------------+------+-----+-----         


        

Answer 1

Use this:

;WITH CTE(Id, Name, parent_id, [Level], ord) AS (
    SELECT 
        MySiteMap.Id, 
        CONVERT(nvarchar(255), MySiteMap.Name) AS Name, 
        MySiteMap.parent_id, 
        1,
        CONVERT(nvarchar(255), MySiteMap.Id) AS ord
    FROM MySiteMap
    WHERE MySiteMap.parent_id IS NULL
    UNION ALL
    SELECT 
        MySiteMap.Id, 
        CONVERT(nvarchar(255), REPLICATE(' ', [Level]) + '|' + REPLICATE(' ', [Level]) + MySiteMap.Name) AS Name, 
        MySiteMap.parent_id, 
        CTE.[Level] + 1,
        CONVERT(nvarchar(255),CTE.ord + CONVERT(nvarchar(255), MySiteMap.Id)) AS ord
    FROM MySiteMap
        JOIN CTE ON MySiteMap.parent_id =CTE.Id
    WHERE MySiteMap.parent_id IS NOT NULL
)
SELECT Name
FROM CTE
ORDER BY ord

For this:

A
 | B
  |  B1
  |  B2
 | C
  |  C1
  |  C2
 | D
  |  D1
  |  D2