(:=== XPath Demo ===:)

(:***************************************************************
   SIMPLE PATH EXPRESSION
   All book titles
****************************************************************:)

doc("bookstore.xml")/Bookstore/Book/Title

(:***************************************************************
   ALTERNATIVES (UNION)
   All book or magazine titles
****************************************************************:)

doc("bookstore.xml")/Bookstore/(Book|Magazine)/Title

(:***************************************************************
   WILDCARD
   All titles
****************************************************************:)

doc("bookstore.xml")/Bookstore/*/Title

(:***************************************************************
   OPERATOR // (ALL DESCENDANTS)
   All titles
****************************************************************:)

doc("bookstore.xml")//Title

(:***************************************************************
   COMBINING // AND WILDCARD
   All elements
****************************************************************:)

doc("bookstore.xml")//*

(:***************************************************************
   SELECTING ATTRIBUTES
   All book ISBNs
   [[ Error, then fix with data() ]]
****************************************************************:)

doc("bookstore.xml")/Bookstore/Book/@ISBN



(:***************************************************************
   PATH WITH CONDITION
   All books costing less than $90
****************************************************************:)

doc("bookstore.xml")/Bookstore/Book[@Price < 90]

(:***************************************************************
   CONDITION INSIDE PATH
   Titles of books costing less than $90
****************************************************************:)

doc("bookstore.xml")/Bookstore/Book[@Price < 90]/Title

(:***************************************************************
   EXISTENCE CONDITION
   Titles of books containing a remark
****************************************************************:)

doc("bookstore.xml")/Bookstore/Book[Remark]/Title

(:***************************************************************
   COMPLEX CONDITION
   Titles of books costing less than $90 where "Ullman" is
   an author
   [[ Same query but "Jeffrey Ullman" is an author ]]
   [[ Original query but add "Widom" is not an author ]]
****************************************************************:)

doc("bookstore.xml")/Bookstore/Book[@Price < 90 and
              Authors/Author/Last_Name = "Ullman"]/Title






(:***************************************************************
   Nth ELEMENT
   All second authors [[ also third ]]
****************************************************************:)

doc("bookstore.xml")//Authors/Author[2]

(:***************************************************************
   CONTAINS() PREDICATE
   Titles of books with a remark containing "great"
****************************************************************:)

doc("bookstore.xml")//Book[contains(Remark, "great")]/Title

(:***************************************************************
   "SELF-JOIN"
   All magazines where there's a book with the same title
****************************************************************:)

doc("bookstore.xml")//Magazine[Title = 
                               doc("bookstore.xml")//Book/Title]

(:***************************************************************
   PARENT AXIS AND NAME() FUNCTION
   All elements whose parent tag is not "Bookstore" or "Book"
****************************************************************:)

doc("bookstore.xml")/Bookstore//*[name(parent::*) != "Bookstore"
                              and name(parent::*) != "Book"]

(:***************************************************************
   SIBLING AXIS
   All books and magazines with non-unique titles
   [[ Not quite right, then fix ]]
****************************************************************:)

doc("bookstore.xml")/Bookstore/*[Title = 
                                  following-sibling::*/Title]




(:***************************************************************
   FOR-ALL (KLUDGE)
   Books where every author's first name includes "J"
****************************************************************:)

doc("bookstore.xml")//Book[
            count(Authors/Author[contains(First_Name, "J")]) =
            count(Authors/Author/First_Name)]

(:***************************************************************
   COMPLEX CONDITION REVISITED
   Titles of books costing less than $90 where "Ullman" is
   an author but "Widom is not an author
****************************************************************:)

doc("bookstore.xml")/Bookstore/Book[@Price < 90 and
           Authors/Author/Last_Name = "Ullman" and
           count(Authors/Author[Last_Name = "Widom"]) = 0]/Title