Queries That Return More Than You Want

Suppose you want the titles of all the books. You might decide to define your query like this:


//title

This query does return all titles of books, but it also returns the title of a magazine. This query instructs the XPath processor to start at the root node, search all descendants, and return all title elements. In bookstore.xml, this means that the query returns the title of the magazine in addition to the titles of books. In some other document, if all titles are contained in book elements, this query returns exactly what you want.

To query and obtain only the titles of books, you can use either of the following queries. They obtain identical results. However, the first query runs faster.


/bookstore/book/title //book/title

The first query runs faster because it uses the child axis, while the second query uses the descendent-or-self axis. In general, the simpler axes, such as child, self, parent, and ancestor, are faster than the more complicated axes, such as descendent, preceding, following, preceding-sibling, and following-sibling. This is especially true for large documents. Whenever possible, use a simpler axis.

< Previous| Next >

Learn Convert to XML

Convert to XML lets you convert .txt, binary, and EDI files to XML documents. Convert to XML works on a single document, or to build reusable converters that let you open flat files as XML documents. Free online demonstration!

Learn XQuery

Stylus Studio offers three infomative XQuery demonstration videos illustrating Stylus Studio's XQuery Editor, Mapper, Debugger and other advanced functionality. Watch them today!

MySQL XML Tools

The MySQL tools in Stylus Studio simplify XML related development tasks for working with MySQL and XML.

Convert DTD to XSD

learn how to convert DTD to XML Schema


	Stylus Studio® Developer Network \| Contact Us \| Email this page

Queries That Return More Than You Want

Learn Convert to XML

Learn XQuery

MySQL XML Tools

Convert DTD to XSD

Stylus Most Wanted