Reorder nodes in SQL Hierarchy data type - sql

Question

Using Hierarchy data type on SQL 2008. Nodes in my hierarchy go like this:
value node
36 /8/1/
38 /8/2/
34 /8/3/
40 /8/4/
42 /8/5/
44 /8/6/
46 /8/7/
48 /8/8/
I'd like to rearrange nodes so that /8/3/ and /8/1/ switch places. Any idea on how to do this?
Only idea that I have so far is that I load all nodes on a level in Array, order them the way I want them to be, delete them from table and insert in sorted form.

Answer 1

If (like in your example) you know the hierarchyid values you want to manipulate in advance, you can do it directly, e.g.:
-- Place 1st node between 2nd and 3rd
UPDATE yourTable SET node = CAST('/8/2.5/' AS hierarchyid) WHERE value = 36;
-- Move 3rd node to 1st
UPDATE yourTable SET node = CAST('/8/1/' AS hierarchyid) WHERE value = 34;
If you need to get your new hierarchyid values dynamically, take a look into the GetDescendant() and GetAncestor() functions. Using that, the example would look something like this:
DECLARE #Parent hierarchyid, #Child1 hierarchyid, #Child2 hierarchyid
-- Grab hierarchyids from 2nd and 3rd node
SELECT #Child1 = node FROM yourTable WHERE value = 38;
SELECT #Child2 = node FROM yourTable WHERE value = 34;
-- Get the parent hierarchyid
SELECT #Parent = #Child1.GetAncestor(1);
-- Update 1st node to end up between 2nd and 3rd
UPDATE yourTable SET node = #Parent.GetDescendant(#Child1, #Child2) WHERE value = 36;
-- Update 3rd node to end up before 2nd
UPDATE yourTable SET node = #Parent.GetDescendant(NULL, #Child1) WHERE value = 34;
Note that the hierarchyids do not stay the same in this example. At least one will end up using a 'fraction' for its position (e.g. '/8/2.5/' instead of '/8/3/').

Answer 2

Found the solution
http://technet.microsoft.com/en-us/library/bb677256.aspx