Sie können einen REKURSIVE CTE
dazu:
WITH RECURSIVE Perms(ID, Name, ParentID, CanRead, CanWrite, CanDelete) AS (
SELECT i.ID, i.Name, l.LID AS ParentID, p.CanRead, p.CanWrite, p.CanDelete
FROM Item AS i
LEFT JOIN Permission AS p ON i.ID = p.ID
LEFT JOIN Links AS l ON i.ID = l.ID
), GET_PERMS(ID, ParentID, CanRead, CanWrite, CanDelete) AS (
-- Anchor member: Try to get Read/Write/Delete values from Permission table
SELECT ID, ParentID, CanRead, CanWrite, CanDelete
FROM Perms
WHERE ID = 3
UNION ALL
-- Recursive member: terminate if the previous level yielded a `NOT NULL` result
SELECT p.ID, p.ParentID, p.CanRead, p.CanWrite, p.CanDelete
FROM GET_PERMS AS gp
INNER JOIN Perms AS p ON gp.ParentID = p.ID
WHERE gp.CanRead IS NULL
)
SELECT CanRead, CanWrite, CanDelete
FROM GET_PERMS
WHERE CanRead IS NOT NULL
Der REKURSIVE CTE beendet, wenn eine Berechtigung Datensatz wurde aus der Datenbank abgerufen.
