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XQuery XPath

XQuery uses XPath expressions to restrict the search results on XML collections.

Let's see an example.

Examples​

Consider the following example that contains information about a bookstore.

books.xml
<?xml version="1.0" encoding="UTF-8"?>

<bookstore>
    <book category="children">
        <title lang="en">Harry Potter</title>
        <author>J K. Rowling</author>
        <year>2005</year>
        <price>29.99</price>
    </book>
    <book category="web">
        <title lang="en">XQuery Tips</title>
        <author>Tom Nolan</author>
        <year>2022</year>
        <price>39.99</price>
    </book>
    <book category="web">
        <title lang="en">Learn XML</title>
        <author>Tutorial Reference</author>
        <year>2022</year>
        <price>9.99</price>
    </book>
</bookstore>

We have given here three versions of an XQuery statement that satisfy the same goal of displaying the titles of books that have a price value of less than 30.

1. Read the entire XML document​

The following XQuery document contains the query expression to be executed:

books_ex1.xqy
let $books := doc("books.xml")

for $x in $books/bookstore/book
where $x/price < 30
return $x/title

The result is as follows:

<title lang="en">Harry Potter</title>
<title lang="en">Learn .Net in 24 hours</title>

The result is as follows:

2. Read all the books​

The following XQuery document contains the query expression to be executed:

books_ex2.xqy
let $books := doc("books.xml")/bookstore/book

for $x in $books
where $x/price < 30
return $x/title

The result is as follows:

<title lang="en">Harry Potter</title>
<title lang="en">Learn .Net in 24 hours</title>

3. Read books with price lower than 30​

The following XQuery document contains the query expression to be executed:

books_ex3.xqy
let $books := doc("books.xml")/bookstore/book[price < 30]

for $x in $books
return $x/title

The result is as follows:

<title lang="en">Harry Potter</title>
<title lang="en">Learn .Net in 24 hours</title>

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