Query with where

• List titles of books published by Addison-Wesley

  <bib>
   {
     for $book in doc("bib.xml")/bib/book
     where $book/publisher = "Addison-Wesley"
     return
        $book/title 
    }
  </bib>
  

• This where clause could be replaced by an XPath predicate:

  <bib>
   {
     for $book in doc("bib.xml")/bib/book[publisher="Addison-Wesley"]
     return
        $book/title 
   }
  </bib>

• But where clauses can combine multiple variables from multiple documents

Adapted from XML Query Use Cases