Introduction and use of XQuery and xqj

1. XQuery

XQuery is to XML what SQL is to database tables.

XQuery was designed to query XML data.

XQuery for XML, just like SQL for database tables.

XQuery is designed to query XML data.

W3C specification: http://www.w3schools.com/xquery/

Http://www.w3schools.com/xquery/xquery_reference.asp

XQuery is intuitive and powerful in XML processing. It is supported by various databases based on XPath expressions.

In addition, XQuery is closely related to XPath (the same data model, the same functions and operations ).

Introduction to XQuery: http://www.ibm.com/developerworks/cn/xml/x-xquery.html

XQuery usage: http://www.xquery.com/tutorials/xquery_tutorial/

XQuery: http://www.xquery.com/tutorials/xquery-functions/

Better XQuery tools include xmlspy.

XQuery example:

• Extract information to use in a Web Service
• Generate summary reports
• Transform XML data to XHTML
• Search Web documents for relevant information

Supported operations:

Operator	Description	Example	Return Value
|	Computes two node-Sets	// Book | // CD	Returns a node-set with all book and CD Elements
+	Addition	6 + 4	10
-	Subtraction	6-4	2
*	Multiplication	6*4	24
Div	Division	8 Div 4	2
=	Equal	Price = 9.80	True if price is 9.80 False if price is 9.90
! =	Not equal	Price! = 9.80	True if price is 9.90 False if price is 9.80
<	Less	Price <1, 9.80	True if price is 9.00 False if price is 9.80
<=	Less than or equal	Price <= 9.80	True if price is 9.00 False if price is 9.90
>	Greater	Price> 9.80	True if price is 9.90 False if price is 9.80
> =	Greater than or equal	Price >=9.80	True if price is 9.90 False if price is 9.70
Or	Or	Price = 9.80 or price = 9.70	True if price is 9.80 False if price is 9.50
And	And	Price> 9.00 and price <9.90	True if price is 9.80 False if price is 8.50
MoD	Modulus (Division remainder)	5 mod 2	1

Supported functions:

• Accessor
• Error and trace
• Numeric
• String

• Anyuri
• Boolean
• Duration/date/time
• QNAME

• Node
• Sequence
• Context

Supported data types (derived from XSD 1.0 ):

XSD string

XSD date

XSD numeric

XSD Misc

Misc includes: Boolean, base64binary, hexbinary, float, double, anyuri, QNAME, and notation.

2. xqj

Xqj (XQuery for Java API) is developed as part of Java Community process and JSR 225 with the support of sun.

Using XQuery directly to operate XML, data direct XQuery: http://www.stylusstudio.com/xquery/

Xqj entry: http://www.xquery.com/tutorials/xqj_tutorial/

Using XQuery in Java: http://www.xquery.com/tutorials/xquery-java/

Xqengine: the open source code Query Engine Based on Java. This is a bit backward, because at least the author has abandoned the revision of the tracking specification.

XmlbeansSupport of XQuery: http://xmlbeans.apache.org/docs/2.0.0/guide/conSelectingXMLwithXQueryPathXPath.html

Selectpath for xpath and execquery for XQuery.

SaxonSupport for XQuery: http://saxon.sourceforge.net/

queryExpression.run(dynamicQueryContext, result, props); //http://www.ibm.com/developerworks/cn/xml/x-xquerymashup/

Others:

C ++ XQuery supports xqilla: http://xerces.apache.org/xerces-c/applications.html