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xpath.md

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Below are several XQuery and XPath examples ranging from beginner to advanced, using your

books.xml

file.

Beginner XPath Examples:

  1. Select all book titles:  XPath Query:
      /catalog/book/title

  2. Select all authors:  XPath Query:   /catalog/book/author

  3. Count the number of books:  XPath Query:   count(/catalog/book)

  4. Select books in the "Computer" genre:  XPath Query:   /catalog/book[genre = 'Computer']

Intermediate XPath Examples:

  1. Select books with a price higher than 20:  XPath Query:   /catalog/book[price > 20]

  2. Select the title and publish date for books published after 2000-12-05:  XPath Query:   /catalog/book[publish_date > '2000-12-05']/(title, publish_date)

  3. Select books with titles containing the text "Guide":  XPath Query:   /catalog/book[contains(title, 'Guide')]

Beginner XQuery Examples:

  1. Return all book titles using XQuery:  XQuery:   for $b in doc("books.xml")//book   return $b/title

  2. Return title and author for each book:  XQuery:   for $b in doc("books.xml")//book   return         <title>{ $b/title/text() }</title>     { $b/author/text() }    

Intermediate XQuery Examples:

  1. Filter books with price less than or equal to 10 and return as XML:  XQuery:   for $b in doc("books.xml")//book   where xs:decimal($b/price) <= 10   return         { $b/title }     { $b/author }    

  2. Return books sorted by publish date (ascending):  XQuery:   for $b in doc("books.xml")//book   order by xs:date($b/publish_date)   return $b

Advanced XQuery Examples:

  1. Group books by genre and count the number in each group:  XQuery (using FLWOR and grouping):   for $g in distinct-values(doc("books.xml")//book/genre)   let $books := doc("books.xml")//book[genre = $g]   return         { count($books) }     { $books }    

  2. Return books with detailed info and an extra element showing if the price is considered "Low" (<15), "Medium" (15-30) or "High" (>30):  XQuery:   for $b in doc("books.xml")//book   let $price := xs:decimal($b/price)   let $range :=    if ($price < 15) then 'Low'    else if ($price <= 30) then 'Medium'    else 'High'   return         <title>{ $b/title }</title>     { $b/author }     { $b/price }     <publish_date>{ $b/publish_date }</publish_date>    

  3. Advanced XPath: Using union to return all titles and genres in one result set:  XPath Query:   /catalog/book/title | /catalog/book/genre

Notes:

• Replace doc("books.xml") with the appropriate file path if needed. • These examples assume your XML root is and each element contains common subelements. • Run these queries using an XQuery processor or an XML-enabled IDE (such as VS Code with an XML/XQuery extension).

These examples provide a progressive tutorial from simple XPath selections to advanced XQuery grouping and conditional logic.