Input Functions

XQuery uses input functions to identify the data to be queried. There are two input functions:

1. doc() returns an entire document, identifying the document by a Universal Resource Identifier (URI). To be more precise, it returns the document node.

2. collection() returns a collection , which is any sequence of nodes that is associated with a URI. This is often used to identify a database to be used in a query.

Table 1.1. Entity References Predefined in XQuery

Entity Reference	Character Represented
&lt;	<
&gt;	>
&amp;	&
&quot;	"
&apos;	'

If our sample data is in a file named books.xml , then the following query returns the entire document:

 doc("books.xml") 

A dynamic error is raised if the doc() function is not able to locate the specified document or the collection() function is not able to locate the specified collection.