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

You can use Common Table Expressions.

WITH LeveledSiteMap(Id, Name, Level)
AS
(
    SELECT Id, Name, 1 AS Level
    FROM MySiteMap
    WHERE Parent_Id IS NULL
    UNION ALL
    SELECT m.Id, m.Name, l.Level + 1
    FROM MySiteMap AS m
        INNER JOIN LeveledSiteMap AS l
        ON m.Parent_Id = l.Id
)
SELECT *
FROM LeveledSiteMap