Retrieving Books By Given Author: XQuery Explained

  • Thread starter KataKoniK
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In summary, the conversation discusses writing an XQuery that returns a list of books for a given author. The speaker is questioning how to specify the "given author" and whether it needs to meet certain conditions. The other person suggests simply processing the Author attribute as needed without a "where" statement. The conversation ends with the speaker asking for clarification on the intended goal.
  • #1
KataKoniK
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I have to write an XQuery that for example, "returns a list of books for a given author".

The "given author" in this case can be anything. Therefore, I was wondering what do I need to add to give the query someting, which in return, it will process it.

For example,

for $x in doc("a.xml")/Stuff
where $x/Author = [given author]
return $x/Book
 
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  • #2
If the "given author" can be anything, that means it doesn't need to meet a certain condition in order to be processed, correct? And therefore, you shouldn't need to condition it with a "where" statement.

Merely process the Author attribute as you need it. What is it exactly that you are trying to do?
 
  • #3


In order to retrieve a list of books for a given author using XQuery, you will need to add a variable for the "given author" and use it in your query. This variable can be defined at the beginning of your query, for example:

let $author := [given author]

Then, you can use this variable in your where clause to filter the results by the given author:

for $x in doc("a.xml")/Stuff
where $x/Author = $author
return $x/Book

This will return a list of books where the author matches the given author variable. You can also use the variable in other parts of your query, such as in the return statement to specify which information you want to retrieve for the given author.

Overall, by adding a variable for the given author and using it in your query, you can easily retrieve a list of books for that specific author using XQuery.
 

Related to Retrieving Books By Given Author: XQuery Explained

1. What is XQuery?

XQuery is a query language used for retrieving and manipulating data from XML documents. It is similar to SQL, but specifically designed for working with XML data.

2. How is XQuery used for retrieving books by a given author?

XQuery can be used to search through XML documents and select specific elements or attributes based on given criteria. In this case, the query would be written to select all book elements with the specified author attribute.

3. Can XQuery be used for retrieving books by authors in different languages?

Yes, XQuery is designed to work with any XML document, regardless of the language used. As long as the author information is stored in the XML document, XQuery can retrieve books by any author, regardless of their language.

4. Are there any limitations to using XQuery for retrieving books?

XQuery is a powerful tool for retrieving data from XML documents, but it does have some limitations. It may not be the best choice for complex queries involving multiple documents or large datasets. It is also primarily designed for querying data, not for updating or modifying it.

5. Are there any resources available for learning more about XQuery?

Yes, there are many resources available for learning about XQuery, including online tutorials, books, and forums. Some popular resources include the official W3C XQuery specification, the "XQuery in a Nutshell" book by Priscilla Walmsley, and the XQuery tag on Stack Overflow.

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