XQuery Interview Questions and Answers for 7 years experience

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100 XQuery Interview Questions and Answers (7 Years Experience)

  1. What is XQuery and what are its primary uses?

    • Answer: XQuery is a query language for XML data. Its primary uses include querying, manipulating, and transforming XML documents. It's used extensively in data integration, web services, and applications dealing with semi-structured data.

  2. Explain the difference between XQuery and XPath.

    • Answer: XPath is a language for navigating XML documents and selecting nodes. XQuery, on the other hand, is a more powerful language that allows not only selecting nodes but also constructing new XML documents, performing computations, and manipulating data. XPath is often used *within* XQuery expressions.

  3. Describe the FLWOR expression in XQuery. Give an example.

    • Answer: FLWOR stands for "For, Let, Where, Order By, Return." It's the core construct in XQuery for processing sequences of data. For iterates over a sequence, Let assigns variables, Where filters the sequence, Order By sorts the sequence, and Return specifies the output. Example: `for $x in /books/book where $x/price > 50 return $x/title`

  4. How do you handle XML namespaces in XQuery?

    • Answer: XML namespaces are handled using the `declare namespace` directive. This assigns a prefix to a namespace URI, allowing you to refer to elements and attributes within that namespace using the prefix. For example: `declare namespace ns1 = "http://example.org/namespace";`

  5. Explain the concept of XQuery functions. Give an example of a user-defined function.

    • Answer: XQuery supports user-defined functions that encapsulate reusable logic. They are defined using the `declare function` keyword. Example: `declare function local:sum($a,$b) { $a + $b };`

  6. What are different data types supported in XQuery?

    • Answer: XQuery supports various data types including xs:string, xs:integer, xs:decimal, xs:boolean, xs:dateTime, xs:date, xs:time, and others from the XML Schema definition language (XSD).

  7. How do you handle errors in XQuery?

    • Answer: Error handling in XQuery is often done using `try...catch` blocks. The `try` block contains the code that might throw an error, and the `catch` block handles the exception.

  8. Explain the use of XQuery's `let` clause.

    • Answer: The `let` clause in a FLWOR expression allows you to assign values to variables. These variables can then be used later in the expression, improving readability and reusability.

  9. What is the purpose of the `where` clause in a FLWOR expression?

    • Answer: The `where` clause in a FLWOR expression filters the sequence of items produced by the `for` clause. Only items that satisfy the condition in the `where` clause are passed to the `return` clause.

  10. How do you sort results using XQuery?

    • Answer: The `order by` clause in a FLWOR expression is used to sort the results. You can specify ascending or descending order.

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