Markus Jarderot's link gives a good answer for this. I end tried using his answer and also tried rewriting my problem in C# and linq but it ended up being more of a mathematical problem than a coding problem because I had a table with several thousands of point that interlinked. This is still something I am interested in and trying to get a better understanding of by reading books on mathematics and graph theory but if anyone else runs into this problem I think Markus Jarderot's link is the best answer you will find.
How do I do a WHERE NOT IN for Hierarchical data?
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30-11-2021 - |
Question
I have a table that is a list of paths between points. I want to create a query to return a list with pointID and range(number of point) from a given point. But have spent a day trying to figure this out and haven't go any where, does any one know how this should be done? ( I am writing this for MS-SQL 2005)
-- fromPointID | toPointID |
---------------|-----------|
-- 1 | 2 |
-- 2 | 1 |
-- 1 | 3 |
-- 3 | 1 |
-- 2 | 3 |
-- 3 | 2 |
-- 4 | 2 |
-- 2 | 4 |
with PointRanges ([fromPointID], [toPointID], [Range])
AS
(
-- anchor member
SELECT [fromPointID],
[toPointID],
0 AS [Range]
FROM dbo.[Paths]
WHERE [toPointID] = 1
UNION ALL
-- recursive members
SELECT P.[fromPointID],
P.[toPointID],
[Range] + 1 AS [Range]
FROM dbo.[Paths] AS P
INNER JOIN PointRanges AS PR ON PR.[toPointID] = P.[fromPointID]
WHERE [Range] < 5 -- This part is just added to limit the size of the table being returned
--WHERE P.[fromPointID] NOT IN (SELECT [toPointID] FROM PointRanges)
--Cant do the where statment I want to because it wont allow recurssion in the sub query
)
SELECT * FROM PointRanges
--Want this returned
-- PointID | Range |
-----------|-------|
-- 1 | 0 |
-- 2 | 1 |
-- 3 | 1 |
-- 4 | 2 |
No correct solution
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