XQuery Functions

XQuery 1.0, XPath 2.0, and XSLT 2.0 share the same functions library.

A list of different types of XQuery functions:

Accessor Functions
Error and Trace Functions
Numeric Functions
String Functions
AnyURI Functions
Boolean Functions
Duration/Date/Time Functions
QName Functions
Node Functions
Sequence Functions
Context Functions

Functions are specified with fn: prefix. For example: fn:string(). But fn: is the default prefix of the namespace, so you do not need to be prefix fn when function is called.

Accessor Functions

Index	Name	Description
1)	fn:node-name(node)	It is used to return the node-name of the argument node.
2)	fn:nilled(node)	It is used to return a Boolean value indicating whether the argument node is nil.
3)	fn:data(item.item,...)	It is used to take a sequence of items and return a sequence of atomic values.
4)	fn:base-uri() fn:base-uri(node)	It returns the value of the base-uri property of the current or specified node.
5)	fn:document-uri(node)	It returns the value of the document-uri property for the specified node.

Error and Trace Functions

Index	Name	Description
1)	fn:error() fn:error(error) fn:error(error,description) fn:error(error,description,error-object)	Example: error(fn:qname('http://example.com/test', 'err:toohigh'), 'error: price is too high')result: returns http://example.com/test#toohigh and the string "error: price is too high" to the external processing environment.
2)	fn:trace(value,label)	it is used to debug queries.

Numeric Values Functions

Index	Name	Description
1)	fn:abs(num)	It returns the absolute value of the argument. For example: abs(3.14) Result: 3.14
2)	fn:abs(num)	It returns the absolute value of the argument For example: abs(3.14) Result: 3.14 Example: abs(-3.14) Result: 3.14
3)	fn:ceiling(num)	It returns the smallest integer that is greater than the number argument For example: ceiling(3.14) Result: 4
4)	fn:floor(num)	It returns the largest integer that is not greater than the number argument For example: floor(3.14) Result: 3
5)	fn:round(num)	It is used to round of the number argument to the nearest integer For example: round(3.14) Result: 3
6)	fn:round-half-to-even()	Example: round-half-to-even(0.5) Result: 0 Example: round-half-to-even(1.5) Result: 2 Example: round-half-to-even(2.5) Result: 2

String Functions

There is a lot of string functions used in XQuery but here we are using the selected one.

A list of commonly used string manipulation functions of XQuery:

Index	Name	Description
1)	string-length($string as xs:string) as xs:integer	It returns the length of the string.
2)	concat($input as xs:anyatomictype?) as xs:string	It returns the concatenated string as output.
3)	string-join($sequence as xs:string*, $delimiter as xs:string) as xs:string	It returns the combination of items in a sequence separated by a delimiter.

Boolean Value Functions

Index	Name	Description
1)	fn:boolean(arg)	It is used to return a Boolean value for a number, string, or node-set.
2)	fn:not(arg)	It specifies that the argument is first reduced to a Boolean value by applying the Boolean() function. It returns true if the Boolean value is false, and false if the Boolean value is true. For example: not(true()) Result: false
3)	fn:true()	It returns the Boolean value true Example: true() Result: true
4)	fn:false()	It returns the Boolean value false For example: false() Result: false

Time and Date Function

There are a lot of time and date function supported in XQuery but here, we are providing the selected one.

A list of some commonly used date and time functions provided by XQuery:

Index	Name	Description
1)	current-date()	It is used to return the current date.
2)	current-time()	It is used to return the current time.
3)	current-datetime()	It is used to return both the current date and the current time.

Next TopicXQuery Sequences

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