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declare function local:fib($n) {
if ($n = 0) then 0
else if ($n = 1) then 1
else local:fib($n - 1) + local:fib($n - 2)
};
for $i in 0 to 9 return local:fib($i)Coding works best on desktop or with an external keyboard.
Fibonacci Sequence - Xquery Typing CST Test
Fibonacci Sequence — Xquery Code
Generates first 10 Fibonacci numbers using XQuery recursion.
declare function local:fib($n) {
if ($n = 0) then 0
else if ($n = 1) then 1
else local:fib($n - 1) + local:fib($n - 2)
};
for $i in 0 to 9 return local:fib($i)Xquery Language Guide
XQuery is a functional, expression-oriented language designed for querying, transforming, and manipulating XML data. It provides powerful tools for navigating hierarchical structures using XPath and is widely used in systems that store or exchange data in XML.
Primary Use Cases
- ▸Querying XML databases (e.g., BaseX, eXist-db, MarkLogic)
- ▸Transforming XML documents
- ▸Integrating heterogeneous data sources
- ▸Building APIs and services that output XML/JSON
- ▸Metadata processing and document-driven workflows
Notable Features
- ▸XPath-based navigation
- ▸Functional expressions and immutability
- ▸FLWOR expressions for structured querying
- ▸Native XML manipulation
- ▸Support for XML, JSON, and text output formats
Origin & Creator
Developed by the W3C XML Query Working Group in the early 2000s as a standard querying language for XML.
Industrial Note
XQuery is especially prominent in enterprise environments involving XML databases, digital publishing, content management, e-commerce feeds, and metadata-heavy systems.
Quick Explain
- ▸XQuery is optimized for querying and transforming XML documents.
- ▸It uses XPath expressions as its foundation for navigating XML structures.
- ▸Commonly used in enterprise systems, content repositories, and applications requiring structured document processing.
Core Features
- ▸FLWOR (For-Let-Where-Order-Return) expressions
- ▸XPath path navigation
- ▸Strong support for hierarchical data
- ▸Typed variables and sequences
- ▸Document construction and transformation
Learning Path
- ▸Start with XPath navigation
- ▸Learn FLWOR expressions
- ▸Practice transformations
- ▸Explore modules and functions
- ▸Optimize with XML database indexing
Practical Examples
- ▸Extract all book titles from an XML library
- ▸Transform XML into HTML
- ▸Generate JSON API responses
- ▸Aggregate metadata across multiple documents
- ▸Filter documents by attribute values
Comparisons
- ▸More powerful than XPath for querying
- ▸More readable than raw DOM manipulation
- ▸More specialized than SQL for hierarchical data
- ▸Less general-purpose than Python or Java
- ▸Often paired with XML databases for best performance
Strengths
- ▸Excellent for complex XML transformations
- ▸Human-readable functional syntax
- ▸High performance with native XML databases
- ▸Supports both querying and document creation
- ▸W3C standard with wide ecosystem support
Limitations
- ▸Niche outside XML-heavy domains
- ▸Not ideal for general-purpose programming
- ▸Learning curve for FLWOR + XPath combination
- ▸Performance can vary on non-native engines
- ▸Limited community compared to mainstream languages
When NOT to Use
- ▸Non-XML data-focused projects
- ▸General application development
- ▸Mobile or web front-end development
- ▸Systems requiring large standard libraries
- ▸JSON-only or SQL-only workflows
Cheat Sheet
- ▸/library/book/title - XPath query
- ▸for $b in /books/book return $b/title
- ▸<new>{/old/text()}</new> - XML construction
- ▸where $x/@id = '123' - attribute filter
- ▸order by $item/price - FLWOR ordering
FAQ
- ▸Is XQuery still relevant?
- ▸Yes - heavily used in XML-centric enterprise systems.
- ▸Can XQuery work with JSON?
- ▸Yes - modern processors support JSON output and manipulation.
- ▸Is XQuery similar to SQL?
- ▸Conceptually yes, but optimized for hierarchical data.
- ▸What database works best with XQuery?
- ▸BaseX, eXist-db, and MarkLogic are top choices.
30-Day Skill Plan
- ▸Week 1: XPath basics
- ▸Week 2: FLWOR expressions
- ▸Week 3: XML transformations
- ▸Week 4: Modules and reusable functions
- ▸Week 5: XML database optimization
Final Summary
- ▸XQuery is a powerful W3C-standard functional language for querying and transforming XML.
- ▸Ideal for hierarchical, metadata-rich, and document-driven systems.
- ▸At its best when paired with native XML databases.
- ▸A key technology in enterprise content and data integration.
Project Structure
- ▸src/ - XQuery modules
- ▸xml/ - XML documents
- ▸lib/ - reusable functions
- ▸tests/ - query tests
- ▸docs/ - documentation and schemas
Monetization
- ▸CMS and publishing tools
- ▸Enterprise data integration
- ▸XML API backends
- ▸Metadata processing solutions
- ▸Consulting for MarkLogic/BaseX deployments
Productivity Tips
- ▸Master XPath first
- ▸Modularize complex transformations
- ▸Use FLWOR for readability
- ▸Validate XML early
- ▸Test queries incrementally
Basic Concepts
- ▸XPath expressions
- ▸Sequences and nodes
- ▸FLWOR expressions
- ▸Types and variables
- ▸XML document construction
Official Docs
- ▸W3C XQuery Specification
- ▸BaseX Documentation
- ▸eXist-db Developer Guides