Let's try to learn some basic XQuery syntax by looking at an example.
从实例直接开始。
We will use the following XML document in the examples below.
先看下面的XML文件
"books.xml":
<?xml version="1.0" encoding="ISO-8859-1"?>
<bookstore>
<book category="COOKING">
<title lang="en">Everyday Italian</title>
<author>Giada De Laurentiis</author>
<year>2005</year>
<price>30.00</price>
</book>
<book category="CHILDREN">
<title lang="en">Harry Potter</title>
<author>J K. Rowling</author>
<year>2005</year>
<price>29.99</price>
</book>
<book category="WEB">
<title lang="en">XQuery Kick Start</title>
<author>James McGovern</author>
<author>Per Bothner</author>
<author>Kurt Cagle</author>
<author>James Linn</author>
<author>Vaidyanathan Nagarajan</author>
<year>2003</year>
<price>49.99</price>
</book>
<book category="WEB">
<title lang="en">Learning XML</title>
<author>Erik T. Ray</author>
<year>2003</year>
<price>39.95</price>
</book>
</bookstore>
--------------------------------------------------------------------------------
How to Select Nodes From "books.xml"?
从"books.xml"中选取结点
Functions
XQuery uses functions to extract data from XML documents.
XQuery利用函数从XML文件中提取数据。（注：本人非理科、非工科、非IT行业，我一看见Functions就会想到“功能”。今天学一个行话，“函数”，不知合适不合适。）
The doc() function is used to open the "books.xml" file:
用doc() 来打开"books.xml"文档：
doc("books.xml")
Path Expressions
XQuery uses path expressions to navigate through elements in an XML document.
XQuery采用路径表达式在XML文件的元素中导航。
The following path expression is used to select all the title elements in the "books.xml" file:
用以下路径表达式在 "books.xml"文档中选取所有的"title"元素：
doc("books.xml")/bookstore/book/title
(/bookstore selects the bookstore element, /book selects all the book elements under the bookstore element, and /title selects all the title elements under each book element)
（/bookstore选取"bookstore"元素；/book选取"bookstore"元素下属的所有"book"元素；/title选取每个"bookstore"元素下属的所有"title"元素）
The XQuery above will extract the following:
以上XQuery提取以下数据：
<title lang="en">Everyday Italian</title>
<title lang="en">Harry Potter</title>
<title lang="en">XQuery Kick Start</title>
<title lang="en">Learning XML</title>
Predicates
XQuery uses predicates to limit the extracted data from XML documents.
谓词
XQuery利用谓词来限定从XML文件中提取的数据。
The following predicate is used to select all the book elements under the bookstore element that have a price element with a value that is less than 30:
以下谓词用以选取"bookstore"元素下属的、拥有"price"元素且"price"元素值小于30的所有"book"元素：
doc("books.xml")/bookstore/book[price<30]
The XQuery above will extract the following:
上述XQuery提取以下数据：
<book category="CHILDREN">
<title lang="en">Harry Potter</title>
<author>J K. Rowling</author>
<year>2005</year>
<price>29.99</price>
</book>
[此贴子已经被作者于2007-4-14 18:18:20编辑过]
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2007/4/12 15:33:00
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