How to find the max attribute from an XML document using Xpath 1.0

Question

Is there a way to query an XML document to return the maximum of a given attribute using Xpath 1.0 ?

For example is there a way to get the max id ?

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Answer 1

XPath 1.0

/library/book[not(@id < /library/book/@id)]

This query style is more generic and works even if books are grouped i.e.

Same query still works (the path should be modified)

/library/genre/book[not(@id < /library/genre/book/@id)]

or even

//book[not(@id < //book/@id)]

To avoid performance troubles use XPath 2 max() instead