📘 XQuery Terms – Essential Vocabulary for Querying XML

🧲 Introduction – Why Learn XQuery Terms?

Before diving deep into coding, it’s important to understand the core vocabulary that XQuery uses. These terms form the foundation of the language and appear in nearly every query you’ll write. Knowing them will help you read, write, and debug XQuery expressions with confidence—whether you’re extracting, filtering, or transforming XML data.

🎯 In this guide, you’ll learn:

• The key terms used in XQuery syntax
• Their roles in navigating and manipulating XML
• Examples of each concept in action
• How these terms relate to XPath and FLWOR expressions

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🧾 Core XQuery Terms & Definitions

Term	Definition
doc()	Function to load an external XML document
node()	A generic term for any XML node (element, attribute, text, etc.)
element()	Refers specifically to XML elements
attribute()	Refers to XML attributes (used with @attr)
text()	Selects text content within an element
/	XPath symbol for absolute path
//	Selects nodes at any level (descendant-or-self axis)
.	Current context node
@	Accesses an attribute of the current node
$	Declares a variable
let	Assigns values to a variable (non-iterative)
for	Iterates over a sequence (like a loop)
where	Filters results based on a condition
order by	Sorts results in ascending/descending order
return	Defines what to output after query execution
if…then…else	Conditional expression for control flow
typeswitch	Branching logic based on data type
sequence	A list of values or nodes (can be mixed)

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📄 Examples of Key Terms in Action

🔹 doc()

doc("books.xml")//book

✅ Loads an external XML file and selects all <book> nodes.

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🔹 @ and text()

for $b in doc("books.xml")//book
return $b/@id

✅ Returns the id attribute of each <book> element.

return $b/title/text()

✅ Returns only the text inside <title> without tags.

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🔹 let and $ Variables

let $price := 499
return <message>Price is {$price}</message>

✅ Stores a value and uses it dynamically in the output.

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🔹 sequence

("XQuery", "XPath", "XSLT")

✅ A valid sequence of strings.

($b/title, $b/author)

✅ A sequence of XML nodes.

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🔍 Related XPath Concepts

XPath Concept	XQuery Equivalent or Use
//book	Same in XQuery for selection
@id	Used to access attributes
text()	Extracts text node from elements
position()	Used in filters and sorting

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💡 Why These Terms Matter

• They define the structure of every XQuery program
• Help you navigate XML and manipulate data effectively
• Are used across XQuery functions, FLWOR, and expressions
• Reduce confusion when combining multiple queries

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✅ Best Practices

• ✔️ Always use doc("file.xml") to load external XML
• ✔️ Use variables (let, $) for reuse and readability
• ✔️ Leverage sequences to return multiple elements cleanly
• ✔️ Use text() or string() for value-only outputs
• ❌ Avoid hardcoding values—prefer XPath and variables

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📌 Summary – Recap & Next Steps

XQuery terms form the building blocks of the language. From loading XML files to looping, filtering, and returning structured data—each keyword and function plays a crucial role in expressing logic in XML querying.

🔍 Key Takeaways:

• XQuery terms like for, let, doc(), return are essential to syntax
• Understanding them boosts fluency and debugging skills
• These terms help bridge the gap between XQuery and XPath

⚙️ Real-world relevance: Mastery of terms helps in writing efficient queries for APIs, dashboards, XML-driven apps, and data pipelines.

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❓ FAQs – XQuery Terms

❓ What does doc() do in XQuery?
✅ Loads an external XML document into memory for querying.

❓ What’s the difference between let and for?
✅ let binds a value once, for iterates over a sequence.

❓ Can I return multiple nodes in XQuery?
✅ Yes. XQuery supports sequences as native outputs.

❓ What’s the use of @ in XQuery?
✅ It’s used to access attributes (e.g., @id, @name).

❓ Is text() required to get element content?
✅ It’s best used when you want only the textual content without XML tags.

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