文件和路径名的SQL递归串联

Question

I just can't wrap my head around this... I have 3 related tables in SQL Server:

FileIds

  Id
  FileName

FolderIds

  Id
  ParentId
  FolderName

FileInfo

  Id
  FolderId
  FileId
  FileAuthorId
  FileClientId

Sample data:

FileIds

  1, Gartner
  2, Parker
  3, Stepp

FolderIds

  1, null, Georgia
  2, 1, Atlanta
  3, 2, Terminus
  4, 3, Suite 1500
  5, 4, David Williams
  6, 4, Lisa Davidson
  7, 2, LaGrange
  8, 7, Dena Pressley

FileInfo

  1, 8, 1, null, null
  2, 5, 2, null, null
  3, 6, 3, null null

Sample output from view:

  Georgia.Atlanta.LaGrange.Dena Pressley:Gartner, null, null
  Georgia.Atlanta.Terminus.Suite 1500.David Williams:Parker, null, null
  Georgia.Atlanta.Terminus.Suite 1500.Lisa Davidson:Stepp, null, null

While this is not for a file directory, it is laid out like one (replace .'s and :'s with \\'s) and I need to create a view that shows the full path... It is easy to put the pieces together in code such as C#, but I can't seem to figure out how to do it in SQL. I have looked up SQL Server's recursive CTE and I'm just not getting it.

Answer 1

This should allow you to start using recursive CTE:

In here I'm only adding the folders, but you can do exactly the same, in another CTE to add the files

WITH folders (Id, ParentId, FolderName) 
AS (
    -- In here you select the first LEVEL
    SELECT Id, ParentId, FolderName FROM FolderIds
    WHERE ParentId IS NULL 
    UNION ALL 
    -- In here you join the previous LEVEL with new relative LEVELS
    SELECT b.Id, b.ParentId, a.FolderName CONCAT ' ' CONCAT b.FolderName
    FROM folders a 
        INNER JOIN FolderIds b 
            ON a.Id = b.ParentId
)
SELECT *
FROM folders