XQuery FLWR Expression Example

List the titles of books published by Morgan Kaufmann in 1998.

  for $b in document("bib.xml")//book

    where $b/publisher = "Morgan Kaufmann"

    and $b/year = "1998"

      return { $b/title }

List each publisher and the average price of its books.

  for $p in distinct(document("bib.xml")//publisher)

    let $a := avg(document("bib.xml")/book[publisher = $p]/price)

    return

      <publisher> 

        <name> { $p/text() } </name>

        <avgprice> { $a } </avgprice> 

      </publisher>