<oo>→<dh> Digital humanities

Maintained by: David J. Birnbaum (djbpitt@gmail.com) Last modified: 2021-12-27T22:03:57+0000

XQuery assignment #3

The assignment

Select one of these texts and spend a few minutes looking at it to familiarize yourself with its overall structure. You may use your own project text or someone else’s. Then use eXide to develop a query or set of queries to explore the text you’ve chosen, that is, to extract and format something interesting about the text. Your XQuery should be more interesting and more sophisticated than just a simple XPath to retrieve the value of a single element, but what you find interesting in the text is for you to discover. We would suggest beginning by formulating the type of question someone might really want to ask about the data and then retrieving the information you need to answer it. Once you’re getting the data you want, try to incorporate your query into a structure that lets you embed the information you’re retrieving inside valid HTML output. Bear in mind:

• XQuery expressions can be simple XPath expressions or more complex FLWOR structures, but for this assignment you need something more sophisticated than a single, simple XPath expression.
• If you embed XQuery inside an HTML element, you need to wrap it in curly braces. If you don’t, you’ll output the literal text that you typed, instead of the results of intepreting it as XQuery. For example, <p>$i</p> outputs a literal dollar sign and a literal letter i inside <p> tags, which is unlikely to be what you want. To output the value of the variable $i, use <p>{$i}</p> instead.
• The FLWOR return statement returns a single sequence. A sequence can be a single value, such as a number or string or XML element. If you want to return more than one item in the return statement, you have to treat them as a single sequence, which you can do by wrapping them in parentheses and separating them with commas. For example, the following structure:

  let $i := 1
  return
  <h2>Here is a title</h2>
  <p>Here is a paragraph</p>

  is not allowed because it returns two things, an <h2> element and a <p> element. But

  let $i := 1
  return
  (<h2>Here is a title</h2>,
  <p>Here is a paragraph</p>)

  is fine because it returns a single thing, which is a sequence of the two elements. Note that to construct the sequence you need both the parentheses and the comma between the items in the sequence.

Because the XML texts that we are using here are under development, they may be inconsistently or incompletely marked up. They are all well formed, however, which means that they can be explored with XML tools, including XQuery. Remember that some may be in namespaces, in which case your queries need to refer to elements in the correct namespace. You can remind yourself of how to declare and use a namespace in XQuery at xquery-abcs.xhtml.