XQuery Introduction

🔍 What is XQuery?

XQuery is a powerful query language designed to retrieve and manipulate data from XML documents. Think of it as SQL for XML - it helps you find, filter, and extract specific information.


(: Simple XQuery example :)
for $book in doc("books.xml")//book
return $book/title

Why Use XQuery?

XQuery simplifies working with XML data by providing intuitive syntax for searching and extracting information. It's perfect for querying XML databases, transforming documents, and combining data from multiple sources efficiently.

🔎

Query XML

Search and filter XML data

📊

Extract Data

Get specific information

🔄

Transform

Reshape XML structure

🔗

Combine

Join multiple XML sources

🔹 Basic XQuery Syntax

XQuery uses simple expressions to query XML:

📄 Sample XML (books.xml):

<library>
    <book>
        <title>XML Basics</title>
        <author>John Doe</author>
        <price>29.99</price>
    </book>
    <book>
        <title>XQuery Guide</title>
        <author>Jane Smith</author>
        <price>39.99</price>
    </book>
</library>

📄 Simple XQuery:

(: Get all book titles :)
doc("books.xml")//book/title

Result:

<title>XML Basics</title>
<title>XQuery Guide</title>

🔹 XQuery Expressions

Common XQuery expressions for querying XML:

🔸 Path Expressions:

(: Navigate XML structure :)
doc("books.xml")/library/book/title

🔸 Filtering with Predicates:

(: Get books under $35 :)
doc("books.xml")//book[price < 35]

🔸 Extracting Text:

(: Get title text only :)
doc("books.xml")//book/title/text()

Result:

XML Basics
XQuery Guide

🔹 XQuery Functions

Built-in functions for data manipulation:

🔸 Count Function:

(: Count total books :)
count(doc("books.xml")//book)

Result:

🔸 Sum Function:

(: Total price of all books :)
sum(doc("books.xml")//book/price)

Result:

69.98

🔸 String Functions:

(: Convert title to uppercase :)
upper-case(doc("books.xml")//book[1]/title)

Result:

XML BASICS

🔹 Conditional Queries

Use conditions to filter results:

(: Get expensive books :)
for $book in doc("books.xml")//book
where $book/price > 30
return $book/title

Result:

<title>XQuery Guide</title>

🔹 Creating New XML

XQuery can construct new XML from existing data:

(: Create summary XML :)
<summary>
{
    for $book in doc("books.xml")//book
    return <item>{$book/title/text()}</item>
}
</summary>

Result:

<summary>
    <item>XML Basics</item>
    <item>XQuery Guide</item>
</summary>

🔹 XQuery vs XSLT

When to use XQuery:

Querying: Extracting specific data from XML
Filtering: Finding elements that match criteria
Calculations: Performing math on XML data
Databases: Working with XML databases

When to use XSLT:

Transformation: Converting XML to HTML/other formats
Styling: Adding presentation to XML
Templates: Reusable transformation patterns

🔹 Common XQuery Functions

doc() - Load XML document
count() - Count elements
sum() - Add numeric values
avg() - Calculate average
max() - Find maximum value
min() - Find minimum value
concat() - Join strings
substring() - Extract part of string

🔍 What is XQuery?

Why Use XQuery?

Query XML

Extract Data

Transform

Combine

🔹 Basic XQuery Syntax

📄 Sample XML (books.xml):

📄 Simple XQuery:

Result:

🔹 XQuery Expressions

🔸 Path Expressions:

🔸 Filtering with Predicates:

🔸 Extracting Text:

Result:

🔹 XQuery Functions

🔸 Count Function:

Result:

🔸 Sum Function:

Result:

🔸 String Functions:

Result:

🔹 Conditional Queries

Result:

🔹 Creating New XML

Result:

🔹 XQuery vs XSLT

When to use XQuery:

When to use XSLT:

🔹 Common XQuery Functions

🧠 Test Your Knowledge

What is XQuery primarily used for?