How to calculate the sum of values in a tree using SQL

Question

I need to sum points on each level earned by a tree of users. Level 1 is the sum of users\' points of the users 1 level below the user. Level 2 is the Level 1 points of the

Answer 1

Ok, this gives you the results you are looking for, but there are no guarantees that I didn't miss something. Consider it a starting point. I used SQL 2005 to do this, SQL 2000 does not support CTE's

WITH Parent (id, GrandParentId, parentId, Points, Level1Points, Level2Points)
AS
(
    -- Find root
    SELECT id,  
            0 AS GrandParentId,
            ParentId,
            Points,
            0 AS Level1Points,
            0 AS Level2Points
    FROM tblPoints ptr
    WHERE ptr.ParentId = 0

    UNION ALL (
    -- Level2 Points
    SELECT pa.GrandParentId AS Id,
            NULL AS GrandParentId,
            NULL AS ParentId,
            0 AS Points, 
            0 AS Level1Points,
            pa.Points  AS Level2Points
    FROM tblPoints pt
            JOIN Parent pa ON pa.GrandParentId = pt.Id 
    UNION  ALL
    -- Level1 Points
    SELECT pt.ParentId AS Id,
            NULL AS GrandParentId,
            NULL AS ParentId,
            0 AS Points, 
            pt.Points AS Level1Points,
            0 AS Level2Points
    FROM tblPoints pt
            JOIN Parent pa ON pa.Id = pt.ParentId AND pa.ParentId IS NOT NULL 
    UNION  ALL
    -- Points
    SELECT pt.id,
            pa.ParentId AS GrandParentId,
            pt.ParentId,
            pt.Points, 
            0 AS Level1Points,
            0 AS Level2Points
    FROM tblPoints pt
            JOIN Parent pa ON pa.Id = pt.ParentId AND pa.ParentId IS NOT NULL )
)
SELECT id, 
    SUM(Points) AS Points,  
    SUM(Level1Points) AS Level1Points,
    CASE WHEN SUM(Level2Points) > 0 THEN  SUM(Level1Points) + SUM(Level2Points) ELSE 0 END AS Level2Points
FROM Parent
GROUP BY id 
ORDER by id