Example Code For User Tree

One of the users on another web site posted a question about how to associate users in a tree-like organization. That web site isn't well suited to posting code or ongoing discussions about code, so I'm going to post the example here. Feel free to discuss as you see fit.DROP TABLE LI_UserLinks
GO
DROP TABLE LI_Users
GO
DECLARE @d1DATETIME
, @d2DATETIME
, @d3DATETIME
, @d4DATETIME
, @d5DATETIME
, @d6DATETIME
, @d7DATETIME
, @d8DATETIME

SELECT @d1 = GetDate()

CREATE TABLE LI_Users (
uidINT
PRIMARY KEY (uid)
)

SELECT @d2 = GetDate()

CREATE TABLE LI_UserLinks (
uid_fromINT
CONSTRAINT XFK01LI_UserLinks FOREIGN KEY (uid_from)
REFERENCES LI_Users (uid)
, uid_toINT
CONSTRAINT SFK01LI_UserLinks FOREIGN KEY (uid_to)
REFERENCES LI_Users (uid)
CONSTRAINT XPKLI_UserLinks PRIMARY KEY (uid_from, uid_to)
)

ALTER TABLE LI_Userlinks
ADD CONSTRAINT XCK01LI_UserLinks CHECK (uid_from != uid_to)

SELECT @d3 = GetDate()

INSERT INTO LI_Users (
uid) SELECT n0 + 10 * n1 + 100 * n2 + 1000 * n3 + 10000 * n4 + 100000 * n5
FROM (SELECT 0 AS n0 UNION SELECT 1 UNION SELECT 2 UNION SELECT 3
UNION SELECT 4 UNION SELECT 5 UNION SELECT 6 UNION SELECT 7
UNION SELECT 8 UNION SELECT 9) AS z0
CROSS JOIN (SELECT 0 AS n1 UNION SELECT 1 UNION SELECT 2 UNION SELECT 3
UNION SELECT 4 UNION SELECT 5 UNION SELECT 6 UNION SELECT 7
UNION SELECT 8 UNION SELECT 9) AS z1
CROSS JOIN (SELECT 0 AS n2 UNION SELECT 1 UNION SELECT 2 UNION SELECT 3
UNION SELECT 4 UNION SELECT 5 UNION SELECT 6 UNION SELECT 7
UNION SELECT 8 UNION SELECT 9) AS z2
CROSS JOIN (SELECT 0 AS n3 UNION SELECT 1 UNION SELECT 2 UNION SELECT 3
UNION SELECT 4 UNION SELECT 5 UNION SELECT 6 UNION SELECT 7
UNION SELECT 8 UNION SELECT 9) AS z3
CROSS JOIN (SELECT 0 AS n4 UNION SELECT 1 UNION SELECT 2 UNION SELECT 3
UNION SELECT 4 UNION SELECT 5 UNION SELECT 6 UNION SELECT 7
UNION SELECT 8 UNION SELECT 9) AS z4
CROSS JOIN (SELECT 0 AS n5 UNION SELECT 1 UNION SELECT 2 UNION SELECT 3
UNION SELECT 4 UNION SELECT 5 UNION SELECT 6 UNION SELECT 7
UNION SELECT 8 UNION SELECT 9) AS z5

SELECT @d4 = GetDate()

INSERT INTO LI_UserLinks (
uid_from, uid_to) SELECT
uid, 100 * uid + n0 + 10 * n1
FROM LI_Users
CROSS JOIN (SELECT 0 AS n0 UNION SELECT 1 UNION SELECT 2 UNION SELECT 3
UNION SELECT 4 UNION SELECT 5 UNION SELECT 6 UNION SELECT 7
UNION SELECT 8 UNION SELECT 9) AS z0
CROSS JOIN (SELECT 0 AS n1 UNION SELECT 1 UNION SELECT 2 UNION SELECT 3
UNION SELECT 4 UNION SELECT 5 UNION SELECT 6 UNION SELECT 7
UNION SELECT 8 UNION SELECT 9) AS z1
WHERE LI_Users.uid BETWEEN 0 AND 99
AND uid != 100 * uid + n0 + 10 * n1

SELECT @d5 = GetDate()

INSERT INTO LI_UserLinks (
uid_from, uid_to) SELECT
uid, 100 * uid + n0 + 10 * n1
FROM LI_Users
CROSS JOIN (SELECT 0 AS n0 UNION SELECT 1 UNION SELECT 2 UNION SELECT 3
UNION SELECT 4 UNION SELECT 5 UNION SELECT 6 UNION SELECT 7
UNION SELECT 8 UNION SELECT 9) AS z0
CROSS JOIN (SELECT 0 AS n1 UNION SELECT 1 UNION SELECT 2 UNION SELECT 3
UNION SELECT 4 UNION SELECT 5 UNION SELECT 6 UNION SELECT 7
UNION SELECT 8 UNION SELECT 9) AS z1
WHERE LI_Users.uid BETWEEN 100 AND 9999

SELECT @d6 = GetDate()

SELECT u.uid, r1.uid_to, r2.uid_to
FROM LI_Users AS u
INNER JOIN LI_UserLinks AS r1
ON (r1.uid_from = u.uid)
INNER JOIN LI_UserLinks AS r2
ON (r2.uid_from = r1.uid_to)
WHERE 1 = u.uid

SELECT @d7 = GetDate()

SELECT Count(DISTINCT u.uid), Count(DISTINCT r1.uid_to), Count(distinct r2.uid_to)
FROM LI_Users AS u
INNER JOIN LI_UserLinks AS r1
ON (r1.uid_from = u.uid)
INNER JOIN LI_UserLinks AS r2
ON (r2.uid_from = r1.uid_to)

SELECT @d8 = GetDate()

SELECT
DateDiff(ms, @d1, @d2)
, DateDiff(ms, @d2, @d3)
, DateDiff(ms, @d3, @d4)
, DateDiff(ms, @d4, @d5)
, DateDiff(ms, @d5, @d6)
, DateDiff(ms, @d6, @d7)
, DateDiff(ms, @d7, @d8)
, DateDiff(ms, @d1, @d8)-PatP