How to use XQuery to search a collection of XML documents

Use the collection() function to load a collection of XML documents and search using FLWOR expressions and XPath filter conditions. For example, use collection('books')//book to find books with "XML" in the title, use where to filter product names with prices greater than 50, or use document-uri() to return matching document paths to achieve efficient cross-file query and data extraction.

XQuery is a powerful query language designed to retrieve and manipulate XML data. If you need to search across a collection of XML documents, XQuery offers concise syntax and built-in functions to locate matching content efficiently. Here's how to do it.

Understand the Collection Function

The collection() function in XQuery is used to access a set of XML documents. It returns a sequence of documents that you can query together. The exact behavior depends on your environment (eg, BaseX, eXist-db, MarkLogic), but generally:

• collection() without arguments may return all documents in a default database.
• You can pass a path or URI: collection('/books') to target specific folders or collections.

Write a Basic Search Query

To find documents containing specific elements or values, use FLWOR expressions (For, Let, Where, Order by, Return). For example, to search for all books with "XML" in the title across a collection:

This iterates over every book element in the collection, checks if the title contains 'XML', and returns matching nodes.

Filter by Element or Attribute Values

You can refine searches using conditions on attributes or nested elements. Suppose each document represents a product and you want products priced over 50:

This returns only the names of items priced above 50 from all XML files in the 'products' collection.

Return Document Metadata or Paths

Sometimes you just want to know which files matched. Use the document-uri() function to get file paths:

This returns the URIs (paths) of documents where Jane Doe is listed as author.

Basically, use collection() to load your XML files, then apply XPath filters and FLWOR logic to search content. The exact setup depends on your XQuery processor, so check its documentation for configuring collections. With practice, you can perform full-text searches, join data across documents, and transform results—all in one expression.

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