Question

I’m trying to list all files in a virtual directory and it’s sub directories. This could be employees in a company with subordinates, this is not a file system. Maybe recursive store procedure may not be the answer.

Scenario:

• Directory Table: DirId, ParentId
• Files Table: FileId, DirId

ParentId is the parent directory and root directory has parentId = NULL… think it’s self explanatory.

Now the problem… I want a list files that exist in a directory and its sub directories.

For just one directory I would create a stored procedure:

SELECT * FROM Files Where DirId = ????

So how would I create a stored procedure to include sub directories? At the moment I am using C# code and looping through each directory. I prefer to use a stored procedure… unless you prove me wrong.

Answer 1

Have a look at using a CTE.

Something like

DECLARE @Directory Table(
    DirId INT,
    ParentId INT
)
DECLARE @Files Table(
    FileId INT, 
    DirId INT
)

INSERT INTO @Directory SELECT 1, NULL
INSERT INTO @Directory SELECT 2, 1
INSERT INTO @Directory SELECT 3, 1
INSERT INTO @Directory SELECT 4, 2

INSERT INTO @Files SELECT 1, 1
INSERT INTO @Files SELECT 2, 1
INSERT INTO @Files SELECT 3, 2
INSERT INTO @Files SELECT 4, 2
INSERT INTO @Files SELECT 5, 3
INSERT INTO @Files SELECT 6, 3
INSERT INTO @Files SELECT 7, 4
INSERT INTO @Files SELECT 8, 4

;WITH Directories AS (
        SELECT  DirId,
                ParentID
        FROM    @Directory
        WHERE   DirId = 2 
        UNION ALL
        SELECT  d.DirId,
                d.ParentID
        FROM    @Directory d INNER JOIN
                Directories p   ON  d.ParentId = p.DirId
)
SELECT  *
FROM    Directories d INNER JOIN
        @Files f ON d.DirId = f.DirId