Cant Cascade Delete

I have a Sql Server 2005 table with 3 fields, an ID field (primary key), a parent ID field, and Name. The parent ID references the ID field (foreign to primary - many to one) within the same table so that records can reference their parent. I would like to place a cascade delete on the ID field so that when the primary ID is removed it will automatically remove all those records with a parent ID that match. Sql server does not allow me to establish this cascade delete.

I was considering a trigger instead but only know how tio use the AFTER paramter and not an alternative.

Thanks

Hello my friend,

I see that you have a tree-like table. You have records that have a parent record, that can have a parent record that can have a parent record in the same table, and so on. The function at the bottom will help. You will need to change the table name from tblTree and the field names ParentID and PageID to whatever you have called them.

Anyway, the function will return a list of all child records. For example, if PageID 2 had childs 5 and 8, and 5 had 3 childs 67, 68, and 70, the resultset would look like the following: -

2
5
67
68
70
8

All you need to do is run a delete against this returned set as follows, which deletes number 2 and all of its children: -

DELETE FROM tblTree WHERE PageID IN (SELECT PageID FROM dbo.fnGetPages(2))

The function is as follows: -

CREATE FUNCTION dbo.fnGetPages
(
@.PageID AS INT
)

RETURNS @.ChildPageIDs TABLE(PageID INT)

AS

BEGIN
INSERT INTO @.ChildPageIDs (PageID)
SELECT PageID FROM tblTree WHERE ParentID = @.PageID

DECLARE @.TempChildPageIDs TABLE(PageID INT)
INSERT INTO @.TempChildPageIDs (PageID)
SELECT PageID FROM @.ChildPageIDs ORDER BY PageID

DECLARE @.ChildPageID AS INT
SET @.ChildPageID = (SELECT TOP 1 PageID FROM @.TempChildPageIDs)

WHILE (@.ChildPageID IS NOT NULL)
BEGIN
INSERT INTO @.ChildPageIDs (PageID)
SELECT PageID FROM dbo.fnGetPages(@.ChildPageID)
DELETE FROM @.TempChildPageIDs WHERE PageID = @.ChildPageID

SET @.ChildPageID = (SELECT TOP 1 PageID FROM @.TempChildPageIDs)
END
RETURN
END

If you have any questions on this, please let me know.

Kind regards

Scotty

|||Excellent stuff. Thank you!