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XSLT XPATH and XQuery Fundamentals Course On UDemy

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Here's a detailed overview of the fundamentals of XSLT, XPath, and XQuery:

XSLT (eXtensible Stylesheet Language Transformations)

What is XSLT?

XSLT is a language used for transforming XML documents into other formats, such as HTML, plain text, or other XML. It defines how to transform XML data by using a set of rules.

Basic Structure of an XSLT Document

xml

<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
    <xsl:template match="/">
        <html>
            <body>
                <!-- Transformation rules go here -->
            </body>
        </html>
    </xsl:template>
</xsl:stylesheet>

Key Components

Templates: Define transformation rules for specific XML elements.
XPath: In XSLT, XPath is used to navigate through the XML document.
Common Elements:
- <xsl:template>: Defines a template.
- <xsl:value-of>: Extracts the value of a selected node.
- <xsl:for-each>: Iterates over a set of nodes.
- <xsl:if>: Adds conditional logic.

Example XSLT

Transforming XML into HTML:

xml

<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
    <xsl:template match="/books">
        <html>
            <body>
                <h1>Book List</h1>
                <ul>
                    <xsl:for-each select="book">
                        <li>
                            <strong><xsl:value-of select="title"/></strong> by <xsl:value-of select="author"/>
                        </li>
                    </xsl:for-each>
                </ul>
            </body>
        </html>
    </xsl:template>
</xsl:stylesheet>

XPath (XML Path Language)

What is XPath?

XPath is a language used for navigating and querying XML documents. It allows you to select nodes or a set of nodes from an XML document.

Basic Syntax

Selecting Nodes:
- /: Selects from the root node.
- //: Selects nodes from the current node that match the selection, regardless of their location.
- @: Selects attributes.

Example XPath Queries

Select all book titles:
xpath
```
//book/title
```
Select authors of books with a price greater than 30:
xpath
```
//book[price > 30]/author
```

XQuery

What is XQuery?

XQuery is a functional query language designed for querying and manipulating XML data. It can be used to extract data, transform it, and generate new XML documents.

Basic Structure

xquery

for $variable in $sequence
let $anotherVariable := expression
where condition
order by $sortExpression
return expression

Example XQuery

Querying books with a price greater than 30:

xquery

for $book in doc("books.xml")/books/book
where $book/price > 30
return <result>
          <title>{$book/title/text()}</title>
          <author>{$book/author/text()}</author>
       </result>

Conclusion

XSLT: Used for transforming XML into various formats.
XPath: A tool for navigating and selecting nodes in XML documents.
XQuery: A powerful language for querying and manipulating XML data.

Understanding these components is essential for effectively working with XML data. If you have any questions or need further details on any specific topic, feel free to ask!