Your xml format is not very well organized. Keys and children are not in any relation except positional, so it is almost impossible to relate them.

You should make children of the key to appear WITHING the parent key, not side by side.

Closest I could get is:

declare @ClientInfo xml =

N'<?xml version="1.0" ?>

<Root>

<key>29</key>

<children>

<key>500</key>

<children>

<key>3000</key>

<children>

<key>70000</key>

</children>

</children>

</children>

<key>50</key>

<children>

<key>600</key>

<children>

<key>3600</key>

<children>

<key>9862</key>

</children>

<children>

<key>9863</key>

</children>

<children>

<key>9864</key>

</children>

</children>

</children>

<key>70</key>

<children>

<key>900</key>

<children>

<key>3700</key>

<children>

<key>7862</key>

</children>

<children>

<key>6863</key>

</children>

<children>

<key>5864</key>

</children>

</children>

<children>

<key>5400</key>

<children>

<key>7892</key>

</children>

<children>

<key>6563</key>

</children>

<children>

<key>5464</key>

</children>

</children>

</children>

</Root>

'

SELECT

ParentID = c.x.value('../key[1]', 'int'),

ChildID = c.x.value('key[1]', 'int')

FROM @ClientInfo.nodes('//children') c(x) -- "//children" means "children nodes at all levels"

GO

The result is:

ParentID ChildID

----------- -----------

29 500

500 3000

3000 70000

29 600

600 3600

3600 9862

3600 9863

3600 9864

29 900

900 3700

3700 7862

3700 6863

3700 5864

900 5400

5400 7892

5400 6563

5400 5464

(17 row(s) affected)

If you change xml structure as suggested, similar construction would work perfectly.

Since preceding-sibling is not supported by sql2008, you could look into >> and << xml operators that I'm not very familiar with.

Some examples are here:

http://stackoverflow.com/questions/3238844/getting-the-following-sibling-in-an-xpath-when-following-axis-is-not-supported

and here

http://dbaspot.com/sqlserver-programming/212706-how-move-xml-nodes-via-xquery-sql-server-2005-a-2.html