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While processing XML documents and datagrams inside the database, you'll frequently find it necessary and convenient to search the content of the document you're processing. We've noted that the xmldom package provides a completely programmatic way of hunting through the entire tree of nodes of an XML document to find what you're looking for. We'll see in this section how XPath's searching of in-memory XML makes it all declarative and so much easier.
We saw in Chapter 2, that XPath expressions provide a compact, declarative syntax to describe any parts of an XML document you would like to address. Let's explore what opportunities exist for the PL/SQL developer to exploit XPath expressions to search in-memory documents.