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XQuery Interview Questions with answers.R4R provide XQuery Languages study materials in easy way.
Introduction of Xquery:
The W3C is finalizing the XQuery specification, aiming for a final release in
late 2002. XQuery is a powerful and convenient language designed for processing
XML data. It is a specification for a query language that allows a user or
programmer to extract information from an Extensible Markup Language (XML) file
or any collection of data that can be XML-like. With XQuery, you can detect
elements and their attributes inside an XML structured document and extract
them. To accomplish this bit of magic, XQuery utilizes XPath expressions to
locate the specified node and divide it from the other components. The syntax is
intended to be easy to understand and use. Using XQuery, it is possible to view
a relational database table as an XML document.
Why Xquery Used:
XQuery is replacing property middleware languages and Web Application
development languages. XQuery is replacing complex Java or C++ programs with a
few lines of code. XQuery is simpler to work with and easier to maintain than
many other alternatives. It is used as a back end for implementing Web sites,
Web project, integrating corporate data stores in the enterprise, in the XRX
architecture (XForms, REST and XQuery), as well as for large publishing
projects, for data mining, and for academic research. It can run on large
servers and on mobile devices, as part of commercial software and as open
Features of XQuery:
Some of the features which are present in XQuery language are as follows: -
1) Logical and physical data independence
3) High level
4) Side effect free
5) Strongly typed language
Difference between XQuery and XSLT.
XSLT is document-driven; XQuery is program driven.
XSLT is functional; XQuery is declarative.
XSLT is written in XML; XQuery is not.
XQuery 1.0 and XPath 2.0:
XQuery makes use of XPath, a language that describes a way to locate and
process items in XML documents. The specifications of XPath and XQuery are
closely related. XQuery 1.0 derives directly from XPath 2.0. In XQuery, XPath
expressions can be simple queries or parts of larger queries. XQuery has
functions for numerous operations including date and time comparisons,
mathematical calculations, string manipulations, and Boolean algebra.
Advantage of Xquery:
XQuery statements are shorter than similar SQL or XSLT programs.
XQuery combines the processing power of XPath and XSLT into one
XQuery can convert XML into almost any output format, from HTML over XHTML
to WML, SVG, SMIL, etc. This allows support not only for HTML clients but also
for mobile clients, and for multimedia applications.
User-definable XQuery functions allow for modular query expressions.
The XML Schema type system and namespaces are fully supported.
XQuery 4 features easy-to-read SQL-like syntax. An alternative syntax (XQueryX)
allows the formulation of queries as XML documents. XQuery 4 also supports
insert, update and delete operations.
XQuery can query both hierarchical and tabular data.
XQuery has a consistent syntax and can be used with other XML standards
such as XML Schema datatypes.
XQuery can query many different data structures and its recursive nature
makes it ideal for querying tree and graph structures.
XQuery can be learned by anyone familiar with SQL.
Both XQuery and SQL have easy ways to select distinct values from a result
Disadvantage of Xquery:
XQuery 1.0 is not yet a W3C Recommendation. Tamino's XQuery 4 supports a
subset of the W3C XQuery Working Draft.
Currently, no WYSIWYG editors exist that can produce XQuery from a web page
design. The same is true for QbE (Query by Example) front-ends.
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