Functions
XQuery uses functions to extract data from XML documents.
The doc() function is used to open the xml file.
Example: doc("books.xml")
Path Expressions
XQuery uses path expressions to navigate through elements in an XML document.
path expression is used to select all the title elements in the "books.xml" file:
doc("books.xml")/bookstore/book/title
/bookstore selects the bookstore element,
/book selects all the book elements under the bookstore element, and
/title selects all the title elements under each book element