XML XQuery Features

• XQuery is a language used to retrieve and manipulate data from XML documents.
• It offers a vast range of features to enable developers to write complex queries and transform XML data.
• Here are some of the key features of XQuery:

Syntax

The syntax of XQuery is similar to that of SQL, but it also includes XML constructs. The basic syntax of an XQuery statement is as follows:

FOR $variable IN collection
WHERE expression
RETURN expression

Example

Consider the following XML document:

<persons>
  <person id="1">
    <name>John</name>
    <age>25</age>
  </person>
  <person id="2">
    <name>Jane</name>
    <age>30</age>
  </person>
</persons>

Here is an example XQuery statement that retrieves the names of all persons in the XML document:

for $person in /persons/person
return $person/name

Output

The output of the XQuery statement above would be:

<name>John</name>
<name>Jane</name>

Explanation

In the XQuery statement above, the for keyword is used to loop through each person element in the XML document. The $person variable is used to represent each person element that is being looped through. The return keyword is used to specify the result of the query. In this case, we are returning the name element of each person.

Use

XQuery is commonly used in applications that deal with XML data, such as document management systems and database applications. It can be used to extract data from XML documents and transform the data into different formats. XQuery can also be used to validate XML documents against schemas.

Important Points

• XQuery is a language used to retrieve and manipulate data from XML documents.
• The syntax of XQuery is similar to that of SQL, but it also includes XML constructs.
• XQuery can be used to extract data from XML documents and transform the data into different formats.
• XQuery can also be used to validate XML documents against schemas.

Summary

In this tutorial, we have introduced the key features of XQuery. We have seen how XQuery can be used to retrieve and manipulate data from XML documents, and how its syntax is similar to that of SQL. We have also discussed how XQuery is commonly used in applications that deal with XML data, and how it can be used to validate XML documents against schemas.