Database Reference
In-Depth Information
More and more data is being stored, exchanged, and presented using XML; and the W3C has developed
recommendations for XQuery, which is a language for querying XML, XSL, XHTML, other XML-based docu-
ments, and similarly structured data repositories. There is growing interest in XQuery, and several products
have been developed based on the XQuery standard.
One example of the inroads made by XML is Microsoft
s Office suite. Starting with the Office 2007 suite,
Microsoft switched from its native file formats to a new file format that it calls Office Open XML for the
Excel, PowerPoint, and Word programs. The Office Open XML file format is a compressed version of XML,
but you can save each of these files in a more traditional XML-based format.
Figure 9-11 illustrates the interaction between XML and the languages that are closely related to XML. A
Web browser can display a Web page by processing an XML document with styles supplied by an XSL docu-
ment. A Web browser can also display a Web page by processing an HTML or XHTML document with styles
supplied by an XSL document; the HTML or XHTML document is created by an XML processor using an
XSLT transform on an XML document. Also, a Web client can obtain information from an XML document by
using an XQuery processor. Finally, an XML processor can create an XML document from data in a database
using a DTD or an XML schema, or the XML processor can update the database using an XML document with
a DTD or an XML schema.
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295
Web browser
uses XML and
XSL documents
to display a
Web page
Web
browser
DTD or
XML schema
XSL
XQuery
processor
XML
document
XML
processor
Web client obtains
information from
an XML document
using XQuery
An XML
processor uses
a DTD or an XML
schema and an
XML document
to interact with a
database server
connected to a
database
Database
server
HTML or
XHTML
XML
processor
Web
browser
XSL
XSLT
An XML processor uses XSLT
to transform an XML document into an
HTML or XHTML document, which a Web
browser uses with an XSL document to
display a Web page
Database
FIGURE 9-11
Interaction among XML and related languages
DATA WAREHOUSES
Among the objectives that organizations have when they use RDBMSs are data integrity, high performance,
and ample availability. The leading RDBMSs are able to satisfy these requirements. Typically, when users
interact with an RDBMS, they use transactions, such as adding a new order and changing a customer
'
s sales
rep. Thus, these types of systems are called online transaction processing (OLTP) systems.
For each transaction, OLTP typically deals with a few rows from the tables in a database in a highly
structured, repetitive, and predetermined way. If you need to know the status of specific customers, parts,
and orders or if you need to update data for specific customers, parts, and orders, an RDBMS and OLTP are
the ideal tools to use.
