XML Demystified

CHAPTER 9 XQuery
You already learned that a function is a task that Saxon-B already knows how to
perform; all you need to do is to call the function in your XQuery whenever you
want Saxon-B to perform that task.
Table 9-2 contains commonly used XQuery functions. You can find a complete
list of functions at www.w3.org/2005/02/xpath-functions.
In addition to calling built-in functions, you can also define your own functions
that can be called the same way a built-in function is called. Here’s what you need
to do. First create the function by writing a function declaration statement.
Function Description Example
upper-case() Converts the argument to
uppercase letters.
lower-case() Converts the argument to
lowercase letters.
upper-case(“Led Zeppelin”)
returns: “LED ZEPPELIN”
lower-case(“Led Zeppelin”)
returns: “led zeppelin”
substring() Returns a substring. substring(“Led Zeppelin”,1, 6)
returns: “Led Ze”
string() Returns the string representation
of the argument.
concat() Returns the concatenation of two
strings.
string-join() Returns a concatenation of the
arguments separated by the
specifi ed separator. The fi rst
argument is a list of strings and the
second argument is the separator.
You may fi nd this particularly
useful for displaying names.
string-length() Returns the length of the string.
If the argument is a node, then
it returns the length of the string
data for that node.
Table 9-2 Commonly Used Built-In XQuery Functions
string(645)
returns: “645” as a string.
concat(“XQu”, “ery”)
returns: “XQuery”
string-join((“Mary”, “Ellen”,
“Smith”), “ “)
returns: “Mary Ellen Smith”
string-length(“Led
Zeppelin”)
returns: 12
141
Functions