SQL Server and XML Support

Extensible Markup Language (XML) is a hypertext programming language used to describe the contents of a set of data and how the data should be output to a device or displayed in a Web page. Markup languages originated as ways for publishers to indicate to printers how the content of a newspaper, magazine, or book should be organized. Markup languages for electronic data perform the same function for electronic documents that can be displayed on different types of electronic gear.

Both XML and the Hypertext Markup Language (HTML) are derived from Standard Generalized Markup Language (SGML). SGML is a very large, complex language that is difficult to fully use for publishing data on the Web. HTML is a more simple, specialized markup language than SGML, but has a number of limitations when working with data on the Web. XML is smaller than SGML and more robust than HTML, so is becoming an increasingly important language in the exchange of electronic data through the Web or intracompany networks.

In a relational database such as Microsoft® SQL Server™ 2000, all operations on the tables in the database produce a result in the form of a table. The result set of a SELECT statement is in the form of a table. Traditional client/server applications that execute a SELECT statement process the results by fetching one row or block of rows from the tabular result set at a time and mapping the column values into program variables. Web application programmers, on the other hand, are more familiar with working with hierarchical representations of data in XML or HTML documents.

SQL Server 2000 introduces support for XML. These new features include:

• The ability to access SQL Server through a URL.
  
  
• Support for XML-Data schemas and the ability to specify XPath queries against these schemas.
  
  
• The ability to retrieve and write XML data:
  • Retrieve XML data using the SELECT statement and the FOR XML clause.
    
    
  • Write XML data using the OpenXML rowset provider.
• Enhancements to the Microsoft SQL Server 2000 OLE DB provider (SQLOLEDB) that allow XML documents to be set as command text and to return result sets as a stream.

See Also

XML and Internet Support Overview

Accessing SQL Server Using a URL

Creating XML Views Using Annotated Schemas

Using XPath Queries

Retrieving and Writing XML Data