xpath: select parent and filtered children

Question

Given an xml block of:

How might I use xpath to re

Answer 1

With just XPath, you can't.

XPath allows you to query (select) nodes from an XML document tree, but it can't modify a tree or create new nodes. So if you select the original <parent> node, it will have two <child> children, and you can't change that. In order to get a <parent> with only one child, you'd have to either modify the original <parent> to delete its other child, or create a new <parent>.

You could do this with XSLT, as you alluded to; or a number of other XML tree-building technologies. If you tell us what kind of platform you're building on, we could suggest ones that are most relevant to your platform.