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HBase, Hadoop, ZooKeeper, Cassandra

Flex4, AS3, Swiz framework, GraniteDS, BlazeDS etc.

There is nothing that software can't fix. Unfortunately, there is also nothing that software can't completely fuck up. That gap is called talent.

About Me

XQuery 語法

What is XQuery?
什么是XQuery？

XQuery is the language for querying XML data
XQuery是查詢XML數(shù)據(jù)的語言
XQuery for XML is like SQL for databases
XQuery與XML的關(guān)系類似于SQL與數(shù)據(jù)庫的關(guān)系
XQuery is built on XPath expressions
XQuery 是建立在XPath表達(dá)式基礎(chǔ)上的
XQuery is defined by the W3C
XQuery是由W3C 定義的
XQuery is supported by all the major database engines (IBM, Oracle, Microsoft, etc.)
所有重要的數(shù)據(jù)庫引擎（如：IBM、Oracle、Microsoft，等等）都支持XQuery
XQuery will become a W3C standard - and developers can be sure that the code will work among different products
XQuery將會(huì)成為W3C的標(biāo)準(zhǔn) —— 開發(fā)者都確信代碼可以在不同的產(chǎn)品之間運(yùn)行

XQuery is About Querying XML
XQuery 是用于查詢XML的

XQuery is a language for finding and extracting elements and attributes from XML documents.
XQuery是用于從XML文檔中查找和提取元素和屬性的語言。

Here is an example of a question that XQuery could solve:
下面是一個(gè)關(guān)于XQuery所能解決的問題的案例：

"Select all CD records with a price less than $10 from the CD collection stored in the XML document called cd_catalog.xml".
從存儲(chǔ)在名為 “cd_catalog.xml” 的XML文檔內(nèi)的CD集中選擇所有價(jià)格低于10美元的CD唱片。

XQuery and XPath
XQuery 和 XPath

XQuery 1.0 and XPath 2.0 share the same data model and support the same functions and operators. If you have already studied XPath you will have no problems with understanding XQuery.
XQuery 1.0 和 XPath 2.0 具有相同的數(shù)據(jù)模型并支持相同的函數(shù)和操作符。如果你已經(jīng)掌握了XPath的相關(guān)知識(shí)，那么，理解XQuery就不成問題了。

You can read more about XPath in our XPath Tutorial.
你可以在我們的XPath 教程中學(xué)習(xí)更多關(guān)于XPath的知識(shí)。

XQuery - Examples of Use
XQuery —— 使用案例

XQuery can be used to:
XQuery 可用于下述操作：

Extract information to use in a Web Service
獲取在Web服務(wù)中使用的信息
Generate summary reports
產(chǎn)生綜合報(bào)告。
Transform XML data to XHTML
把XML數(shù)據(jù)轉(zhuǎn)換成XHTML形式
Search Web documents for relevant information
在Web文檔中搜索相關(guān)信息

XQuery is Not (Yet) a Web Standard
XQuery 并不是網(wǎng)絡(luò)標(biāo)準(zhǔn)

XQuery is compatible with several W3C standards, such as XML, Namespaces, XSLT, XPath, and XML Schema.
XQuery和一些W3C的標(biāo)準(zhǔn)是相互吻合的，例如：XML、Namespaces [命名空間]、XSLT、XPath 和 XML Schema。

However, XQuery 1.0 is not yet a W3C Recommendation (XQuery is a Working Draft). Hopefully it will be a recommendation in the near future.
然而，XQuery 1.0 并不是W3C的推薦標(biāo)準(zhǔn)（XQuery 僅是一份工作草案）。相信在不久的將來，它會(huì)變成 W3C 推薦的標(biāo)準(zhǔn)吧。

Let's try to learn some basic XQuery syntax by looking at an example.
讓我們通過下面這個(gè)案例來學(xué)習(xí)一些關(guān)于XQuery 的基本語法。

The XML Example Document
XML 案例文檔

We will use the following XML document in the examples below.
我們將在下面的案例中使用“books.xml”文檔：

"books.xml":
“books.xml”文件內(nèi)容如下：

<?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>

View the "books.xml" file in your browser.
在瀏覽器中瀏覽“books.xml”文件。

How to Select Nodes From "books.xml"?
如何從"books.xml"文件中選擇節(jié)點(diǎn)？

Functions
函數(shù)

XQuery uses functions to extract data from XML documents.
XQuery 使用函數(shù)從XML文檔中獲取數(shù)據(jù)。

The doc() function is used to open the "books.xml" file:
doc() 函數(shù)用于打開"books.xml"文件：

doc("books.xml")

Path Expressions
路徑表達(dá)式

XQuery uses path expressions to navigate through elements in an XML document.
XQuery 通過路徑表達(dá)式操作XML文檔中的元素。

The following path expression is used to select all the title elements in the "books.xml" file:
下述路徑表達(dá)式用于在"books.xml"文件中選擇 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 選擇 bookstore元素；/book 選擇 bookstore 元素下的所有 book 元素；/title 選擇每個(gè)book 元素下的所有title元素。

The XQuery above will extract the following:
上述的XQuery會(huì)獲取下述內(nèi)容：

<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
條件謂語項(xiàng)

XQuery uses predicates to limit the extracted data from XML documents.
XQuery 使用條件謂語項(xiàng)給從XML文件中摘取的數(shù)據(jù)附加一個(gè)條件。

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:
下面的條件謂語項(xiàng)是用來選擇 bookstore 元素下 price 元素值小于30的所有 book 元素的表達(dá)式：

doc("books.xml")/bookstore/book[price<30]

The XQuery above will extract the following:
上述XQuery語句會(huì)獲取下面的內(nèi)容：

<book category="CHILDREN">

<title lang="en">Harry Potter</title>

<author>J K. Rowling</author>



<year>2005</year>

<price>29.99</price>

</book>

The XML Example Document
XML 案例文檔

We will use the "books.xml" document in the examples below (same XML file as in the previous chapter).
下述案例中，我們會(huì)用到 "books.xml" 文檔（上一章使用的XML文件）。

View the "books.xml" file in your browser.
在你的瀏覽器中瀏覽“books.xml”。

How to Select Nodes From "books.xml" With FLWOR
怎樣使用FLWOR表達(dá)式從"books.xml"文件中選擇節(jié)點(diǎn)

Look at the following path expression:
先看看下面的路徑表達(dá)式：

doc("books.xml")/bookstore/book[price>30]/title

The expression above will select all the title elements under the book elements that are under the bookstore element that have a price element with a value that is higher than 30.
上述表達(dá)式將選擇 bookstore 元素下的 book 元素下的所有price 元素值大于30的 title 元素。

The following FLWOR expression will select exactly the same as the path expression above:
下述FLWOR表達(dá)式和上述路徑表達(dá)式選擇的值相同：

for $x in doc("books.xml")/bookstore/book

            where $x/price>30

            return $x/title

The result will be:
結(jié)果如下：

<title lang="en">XQuery Kick Start</title>

            

            <title lang="en">Learning XML</title>

With FLWOR you can sort the result:
你可以使用FLWOR對(duì)結(jié)果進(jìn)行分類排序：

for $x in doc("books.xml")/bookstore/book

            where $x/price>30

            order by $x/title

            return $x/title

FLWOR is an acronym for "For, Let, Where, Order by, Return".
FLWOR是 "For、Let、Where、Order by、Return" 的首字母縮寫。

The for clause selects all book elements under the bookstore element into a variable called $x.
For子句把 bookstore 元素中的所有 book 元素發(fā)送到名為 $x 的變量?jī)?nèi)。

The where clause selects only book elements with a price element with a value greater than 30.
Where 子句僅選擇price元素值高于30的book元素。

The order by clause defines the sort-order. Will be sort by the title element.
order by 子句定義了“ 分類命令 ”。根據(jù) title 元素進(jìn)行分類。

The return clause specifies what should be returned. Here it returns the title elements.
Return 子句指定了返回的數(shù)據(jù)。這里返回的是 title 元素。

The result of the XQuery expression above will be:
上述 XQuery 表達(dá)式的結(jié)果如下：

<title lang="en">Learning XML</title>

<title lang="en">XQuery Kick Start</title>

The XML Example Document
XML 案例文檔

We will use the "books.xml" document in the examples below (same XML file as in the previous chapters).
下述案例中，我們會(huì)用到 "books.xml" 文檔（上一章使用的XML文件）。

View the "books.xml" file in your browser.
在你的瀏覽器中瀏覽“books.xml”。

Present the Result In an HTML List
在HTML列表中顯示結(jié)果

Look at the following XQuery FLWOR expression:
先看看下面的Query FLWOR表達(dá)式：

for $x in doc("books.xml")/bookstore/book/title

            order by $x

            return $x

The expression above will select all the title elements under the book elements that are under the bookstore element, and return the title elements in alphabetical order.
上述表達(dá)式會(huì)選擇在 bookstore 元素下的 book 元素下所有 title 元素，并按字母順序排列 title 元素后輸出。

Now we want to list all the book-titles in our bookstore in an HTML list. We add <ul> and <li> tags to the FLWOR expression:
現(xiàn)在，我們希望在 HTML列表中列出 bookstore 的所有book-titles元素，因此，我們需要在 FLWOR 表達(dá)式中加入<ul>和<li>標(biāo)簽：

<ul>

            {

            for $x in doc("books.xml")/bookstore/book/title

            order by $x

            return <li>{$x}</li>

            

            }

            </ul>

The result of the above will be:
上述的結(jié)果顯示如下：

<ul>

            <li><title lang="en">Everyday Italian</title></li>

            <li><title lang="en">Harry Potter</title></li>

            <li><title lang="en">Learning XML</title></li>

            

            <li><title lang="en">XQuery Kick Start</title></li>

            </ul>

Now we want to eliminate the title element, and show only the data inside the title element:
現(xiàn)在，我們要除去 title 元素，只顯示 title 元素里的數(shù)據(jù)：

<ul>

            {

            for $x in doc("books.xml")/bookstore/book/title

            order by $x

            return <li>{data($x)}</li>

            

            }

            </ul>

The result will be (an HTML list):
結(jié)果（一份HTML列表）顯示如下：

<ul>

<li>Everyday Italian</li>

<li>Harry Potter</li>

<li>Learning XML</li>

<li>XQuery Kick Start</li>



</ul>

In XQuery, there are seven kinds of nodes: element, attribute, text, namespace, processing-instruction, comment, and document (root) nodes.
在XQuery中，有7中不同的節(jié)點(diǎn)：元素、屬性、文本、命名空間、處理指令、注釋、文檔（根目錄）節(jié)點(diǎn)。

XQuery 術(shù)語

Nodes
節(jié)點(diǎn)

In XQuery, there are seven kinds of nodes: element, attribute, text, namespace, processing-instruction, comment, and document (root) nodes. XML documents are treated as trees of nodes. The root of the tree is called the document node (or root node).
在XQuery里，有7中不同的節(jié)點(diǎn)：元素、屬性、文本、命名空間、處理指令、注釋、文檔（根目錄）節(jié)點(diǎn)，XML文檔是節(jié)點(diǎn)樹狀結(jié)構(gòu)。“樹根”稱作文檔節(jié)點(diǎn)（或根節(jié)點(diǎn)）。

Look at the following XML document:
先看看下面這個(gè)XML文檔：

<?xml version="1.0" encoding="ISO-8859-1"?>

<bookstore>

<book>

            <title lang="en">Harry Potter</title>

            <author>J K. Rowling</author> 

            <year>2005</year>

            

            <price>29.99</price>

            </book>

</bookstore>

Example of nodes in the XML document above:
上述XML文檔中的節(jié)點(diǎn)案例：

<bookstore>  (document node)

<author>J K. Rowling</author>  (element node)

lang="en"  (attribute node)

Atomic values
“原子值”屬性值

Atomic values are nodes with no children or parent.
“原子值”屬性值只沒有子節(jié)點(diǎn)和父節(jié)點(diǎn)。

Example of atomic values:
“原子值”屬性值案例：

J K. Rowling

"en"

Items
項(xiàng)

Items are atomic values or nodes.
“項(xiàng)”是指原子值或節(jié)點(diǎn)。

Relationship of Nodes
節(jié)點(diǎn)間關(guān)系

Parent
父類

Each element and attribute has one parent.
每個(gè)元素和屬性都包含一個(gè)“父類”。

In the following example; the book element is the parent of the title, author, year, and price:
在下述案例中：book元素是title、author、year 和 price 元素的父類元素：

<book>

            <title>Harry Potter</title>

            

            <author>J K. Rowling</author>

            <year>2005</year>

            <price>29.99</price>

            </book>

Children
子類元素

Element nodes may have zero, one or more children.
元素節(jié)點(diǎn)可以包含任意個(gè)數(shù)的子類元素。

In the following example; the title, author, year, and price elements are all children of the book element:
在下述案例中，title、author、year 和 price元素都是book元素的子元素：

<book>

            <title>Harry Potter</title>

            <author>J K. Rowling</author>

            <year>2005</year>

            

            <price>29.99</price>

            </book>

Siblings
同類元素

Nodes that have the same parent.
擁有相同的父類元素的節(jié)點(diǎn)稱為同類元素。

In the following example; the title, author, year, and price elements are all siblings:
在下述案例中，title、author、year 和 price 元素都是“同類元素”：

<book>

            <title>Harry Potter</title>

            <author>J K. Rowling</author>

            

            <year>2005</year>

            <price>29.99</price>

            </book>

Ancestors
祖類元素

A node's parent, parent's parent, etc.
一個(gè)節(jié)點(diǎn)的父類元素，父類元素的父類元素，以此類推，稱為該節(jié)點(diǎn)的祖類元素。

In the following example; the ancestors of the title element are the book element and the bookstore element:
在下述案例中，title元素的 “祖類元素” 是 book 元素和 bookstore 元素。

<bookstore>

<book>

            

            <title>Harry Potter</title>

            <author>J K. Rowling</author>

            <year>2005</year>

            <price>29.99</price>

            

            </book>

</bookstore>

Descendants
孫類元素

A node's children, children's children, etc.
一個(gè)節(jié)點(diǎn)的子類元素，子類元素的子類元素，以此類推，稱為孫類元素。

In the following example; descendants of the bookstore element are the book, title, author, year, and price elements:
在下述案例中，bookstore 元素的孫類元素是book、title、author、year 和 price 元素：

<bookstore> <book>
<title>Harry Potter</title>
<author>J K. Rowling</author>

<year>2005</year>
<price>29.99</price>
</book> </bookstore>

XQuery is case-sensitive and XQuery elements, attributes, and variables must be valid XML names.
Xquery 區(qū)分字母大小寫，它的元素、屬性、變量必須是有效的XML名稱。

XQuery Basic Syntax Rules
XQuery 的基本語法規(guī)則

Some basic syntax rules:
一些基本語法規(guī)則：

XQuery is case-sensitive
XQuery 區(qū)分字母大小寫
XQuery elements, attributes, and variables must be valid XML names
它的元素、屬性、變量必須是有效的XML名稱
An XQuery string value can be in single or double quotes
一個(gè) XQuery 字符串值可以寫在單引號(hào)里或雙引號(hào)里
An XQuery variable is defined with a $ followed by a name, e.g. $bookstore
一個(gè) XQuery 變量定義是在“$”的符號(hào)后面跟上名稱等，例如：$bookstore
XQuery comments are delimited by (: and :), e.g. (: XQuery Comment :)
XQuery 注釋使用 “(: ”和“ :)” 進(jìn)行分界，例如 (: XQuery Comment :)

XQuery Conditional Expressions
XQuery 的條件表達(dá)式

"If-Then-Else" expressions are allowed in XQuery.
XQuery 允許使用 "If-Then-Else" 條件表達(dá)式。

Look at the following example:
先看看下面的案例：

for $x in doc("books.xml")/bookstore/book

            return	if ($x/@category="CHILDREN")

            then <child>{data($x/title)}</child>

            else <adult>{data($x/title)}</adult>

Notes on the "if-then-else" syntax: parentheses around the if expression are required. else is required, but it can be just else ().
使用“if-then-else"條件語句時(shí)應(yīng)注意的語法點(diǎn)：if 表達(dá)式允許出現(xiàn)圓括號(hào)；另外，如果使用了“if”，就必須使用“else”，也可以是else()。

The result of the example above will be:
上述案例輸出的結(jié)果如下：

<adult>Everyday Italian</adult>

            <child>Harry Potter</child>

            <adult>Learning XML</adult>

            <adult>XQuery Kick Start</adult>

XQuery Comparisons
XQuery 比較

In XQuery there are two ways of comparing values.
XQuery 有兩種比較值的方法。

1. General comparisons: =, !=, <, <=, >, >=
常規(guī)比較符號(hào)：= 、 != 、 < 、 <= 、 > 、 >=

2. Value comparisons: eq, ne, lt, le, gt, ge
值的比較：eq 、 ne 、 lt 、 le 、 gt 、 ge

The difference between the two comparison methods are shown below.
下面列舉了兩種比較方法的不同之處。

Look at the following XQuery expressions:
先看看下面的XQuery表達(dá)式：

$bookstore//book/@q > 10

The expression above returns true if any q attributes

have values greater than 10.

如果所有上述q的屬性值大于10，那么，表達(dá)式將返回“true”（真）

$bookstore//book/@q gt 10

The expression above returns true if there is only one

q attribute returned by the expression, and its value

is greater than 10. If more than one q is returned,

an error occurs.

如果表達(dá)式返回的q屬性中，只有一個(gè)q值大于10，那么，上述表達(dá)式才返回“true”（真）；否則

The XML Example Document
XML 案例文檔

We will use the "books.xml" document in the examples below (same XML file as in the previous chapters).
下述案例中，我們會(huì)用到 "books.xml" 文檔（上一章使用的XML文件）。

View the "books.xml" file in your browser.
在你的瀏覽器中瀏覽“books.xml”。

Adding Elements and Attributes to the Result
向結(jié)果中添加元素和屬性

As we have seen in a previous chapter, we may include elements and attributes from the input document ("books.xml) in the result:
就像在前幾章中所看到的，我們可以把來自輸入文檔("books.xml)的元素和屬性添加到結(jié)果中：

for $x in doc("books.xml")/bookstore/book/title

            order by $x

            return $x

The XQuery expression above will include both the title element and the lang attribute in the result, like this:
上述 XQuery 表達(dá)式會(huì)將 title 元素和 lang 屬性添加到結(jié)果中，如下所示：

<title lang="en">Everyday Italian</title>

            

            <title lang="en">Harry Potter</title>

            <title lang="en">Learning XML</title>

            <title lang="en">XQuery Kick Start</title>

The XQuery expression above returns the title elements the exact same way as they are described in the input document.
上述 XQuery 表達(dá)式獲取了 title 元素，它們和原來在輸入文檔中被描述的一樣。

We now want to add our own elements and attributes to the result!
現(xiàn)在，我們希望把我們自己的元素和屬性添加到結(jié)果中。

Add HTML Elements and Text
添加 HTML 元素和文本

Now, we want to add some HTML elements to the result. We will put the result in an HTML list - together with some text:
現(xiàn)在，我們希望將一些HTML元素添加到結(jié)果中。我們將把結(jié)果連同一些文本內(nèi)容放在一個(gè)HTML列表中：

<html>

            <body>

<h1>Bookstore</h1>

<ul>

            {

            for $x in doc("books.xml")/bookstore/book

            order by $x/title

            return <li>{data($x/title)}. Category: {data($x/@category)}</li>

            

            }

            </ul>

</body>

            </html>

The XQuery expression above will generate the following result:
上述XQuery表達(dá)式將會(huì)輸出下面的結(jié)果：

<html>

            <body>

<h1>Bookstore</h1>

<ul>

            <li>Everyday Italian. Category: COOKING</li>

            

            <li>Harry Potter. Category: CHILDREN</li>

            <li>Learning XML. Category: WEB</li>

            <li>XQuery Kick Start. Category: WEB</li>

            </ul>

</body>

            </html>

Add Attributes to HTML Elements
向HTML元素中添加屬性

Next, we want to use the category attribute as a class attribute in the HTML list:
接下來，我們希望把 category 屬性作為 HTML 列表的一個(gè)類屬性：

<html>

            

            <body>

<h1>Bookstore</h1>

<ul>

            {

            for $x in doc("books.xml")/bookstore/book

            order by $x/title

            return <li class="{data($x/@category)}">{data($x/title)}</li>

            }

            

            </ul>

</body>

            </html>

The XQuery expression above will generate the following result:
上述XQuery表達(dá)式將會(huì)輸出下面的結(jié)果：

<html>
<body> <h1>Bookstore</h1> <ul>
<li class="COOKING">Everyday Italian</li>

<li class="CHILDREN">Harry Potter</li>
<li class="WEB">Learning XML</li>
<li class="WEB">XQuery Kick Start</li>
</ul> </body>
</html>

Selecting and Filtering Elements
選擇和過濾元素

As we have seen in the previous chapters, we are selecting and filtering elements with either a Path expression or with a FLWOR expression.
如同在前幾章里所看到的那樣，我們使用路徑表達(dá)式或FLWOR表達(dá)式來選擇和過濾元素。

Look at the following FLWOR expression:
先看看下面的FLWOR表達(dá)式：

for $x in doc("books.xml")/bookstore/book

            where $x/price>30

            order by $x/title

            return $x/title

for - (optional) binds a variable to each item returned by the in expression
for -（可選的）給從 “in 表達(dá)式” 內(nèi)返回每一個(gè)項(xiàng)綁定一個(gè)變量
let - (optional)
let -（可選的）
where - (optional) specifies a criteria
where -（可選的）指定了一個(gè)標(biāo)準(zhǔn)
order by - (optional) specifies the sort-order of the result
order by - （可選的）指定了結(jié)果的排列次序
return - specifies what to return in the result
return - 指定了在結(jié)果中返回的內(nèi)容

The for Clause
For 子句

The for clause binds a variable to each item returned by the in expression. The for clause results in iteration. There can be multiple for clauses in the same FLWOR expression.
給從 “in 表達(dá)式” 中返回每一個(gè)項(xiàng)綁定一個(gè)變量。For子句會(huì)導(dǎo)致重復(fù)。在相同的FLWOR表達(dá)式中，可以包含多個(gè)for子句。

To loop a specific number of times in a for clause, you may use the to keyword:
在for子句中對(duì)一個(gè)指定的數(shù)字進(jìn)行多次循環(huán)，你可以使用關(guān)鍵詞 “ to ”：

for $x in (1 to 5)

            return <test>{$x}</test>

Result:
結(jié)果：

<test>1</test>

            <test>2</test>

            <test>3</test>

            <test>4</test>

            

            <test>5</test>

The at keyword can be used to count the iteration:
關(guān)鍵字 “at” 可用于計(jì)算重復(fù)次數(shù)：

for $x at $i in doc("books.xml")/bookstore/book/title

            return <book>{$i}. {data($x)}</book>

Result:
結(jié)果如下：

<book>1. Everyday Italian</book>

            <book>2. Harry Potter</book>

            <book>3. XQuery Kick Start</book>

            

            <book>4. Learning XML</book>

It is also allowed with more than one in expression in the for clause. Use comma to separate each in expression:
在for子句中，允許出現(xiàn)一項(xiàng)或多項(xiàng) “in 表達(dá)式”；使用逗號(hào)將表達(dá)式中的每項(xiàng)分開：

XQuery 1.0, XPath 2.0, and XSLT 2.0 share the same functions library.
XQuery 1.0、XPath 2.0 和 XSLT 2.0 包含相同的函數(shù)庫。

XQuery Functions
XQuery 函數(shù)

XQuery includes over 100 built-in functions. There are functions for string values, numeric values, date and time comparison, node and QName manipulation, sequence manipulation, Boolean values, and more. You can also define your own functions in XQuery.
XQuery 包括超過100個(gè)內(nèi)置函數(shù)，具體如下：字符串值、數(shù)值、日期時(shí)間值、節(jié)點(diǎn)以及QName操作、排序操作、邏輯值等函數(shù)。你也可以在XQuery內(nèi)定義自己的函數(shù)。

XQuery Built-in Functions
XQuery 內(nèi)置函數(shù)

The URI of the XQuery function namespace is:
http://www.w3.org/2005/02/xpath-functions

XQuery函數(shù)名稱空間（namespaces）的URI是：
http://www.w3.org/2005/02/xpath-functions

The default prefix for the function namespace is fn:.
默認(rèn)的函數(shù)命名空間前綴是fn:.

Tip: Functions are often called with the fn: prefix, such as fn:string(). However, since fn: is the default prefix of the namespace, the function names do not need to be prefixed when called.
提示：函數(shù)常常以“fn:”為前綴名調(diào)用，例如fn:string()；然而，因?yàn)閒n:是命名空間的默認(rèn)前綴，所以這個(gè)函數(shù)的名稱并不需要通過前綴名來調(diào)用。

The reference of all the built-in XQuery 1.0 functions is located in our XPath tutorial.
XQuery 1.0內(nèi)置函數(shù)參考。

Examples of Function Calls
函數(shù)調(diào)用實(shí)例

A call to a function can appear where an expression may appear. Look at the examples below:
函數(shù)調(diào)用可以出現(xiàn)在一個(gè)表達(dá)式中所有可能出現(xiàn)的地方，看下面的案例：

Example 1: In an element
例1：在一個(gè)元素中：

<name>{uppercase($booktitle)}</name>

Example 2: In the predicate of a path expression
例2：在路徑表達(dá)的條件謂語項(xiàng)中：

doc("books.xml")/bookstore/book[substring(title,1,5)='Harry']

Example 3: In a let clause
例3：在let子句中：

let $name := (substring($booktitle,1,4))

XQuery User-Defined Functions
XQuery 用戶自定義函數(shù)

If you cannot find the XQuery function you need, you can write your own.
如果你找不到需要使用的XQuery函數(shù)，你可以自己書寫。

User-defined functions can be defined in the query or in a separate library.
用戶自定義函數(shù)可以在查詢語句或獨(dú)立庫中進(jìn)行定義。

Syntax
語法

declare function prefix:function_name($parameter AS datatype)

            AS returnDatatype

            {

(: ...function code here... :)

};

Notes on user-defined functions:
用戶自定義函數(shù)需要注意以下幾點(diǎn)：

Use the declare function keyword
使用 “declare function（函數(shù)聲明）” 關(guān)鍵詞
The name of the function must be prefixed
函數(shù)名稱要必須包含前綴
The data type of the parameters are mostly the same as the data types defined in XML Schema
參數(shù)的數(shù)據(jù)類型要和在XML Schema中定義的數(shù)據(jù)類型基本一致
The body of the function must be surrounded by curly braces
函數(shù)的主體部分必須在圓括號(hào)內(nèi)書寫

Example of a User-defined Function Declared in the Query
在查詢語句里聲明的用戶自定義函數(shù)案例

declare function local:minPrice(
$price as xs:decimal?,
$discount as xs:decimal?)
AS xs:decimal?
{
let $disc := ($price * $discount) div 100
return ($price - $disc)
}; (: Below is an example of how to call the function above :) <minPrice>{local:minPrice($book/price, $book/discount)}</minPrice>

XQuery Summary
XQuery 概要

This tutorial has taught you how to query XML data.
這篇教程將教你如何查詢XML數(shù)據(jù)。

You have learned that XQuery was designed to query anything that can appear as XML, including databases.
你應(yīng)該已經(jīng)了解：XQuery是用于查詢包括數(shù)據(jù)庫在內(nèi)的以XML形式出現(xiàn)的任何內(nèi)容。

You have also learned how to query the XML data with FLWOR expressions, and how to construct XHTML output from the collected data.
你應(yīng)該已經(jīng)了解怎樣使用FLWOR表達(dá)式查詢XML數(shù)據(jù)，以及怎樣從已選數(shù)據(jù)里構(gòu)建XHTML結(jié)果。

For more information on XQuery, please look at our XQuery Reference.
在我們的XQuery 參考上有關(guān)于XQuery的更多內(nèi)容。

Now You Know XQuery, What's Next?
學(xué)會(huì)了XQuery，接下來該學(xué)些什么呢？

The next step is to learn about XLink and XPointer.
下一步是學(xué)習(xí)與 XLink 和 XPointer 相關(guān)的內(nèi)容。

XLink and XPointer

Linking in XML is divided into two parts: XLink and XPointer.
XML中的鏈接分為兩個(gè)部分：XLink 和XPointer。

XLink and XPointer define a standard way of creating hyperlinks in XML documents.
XLink 和 XPointer 定義了在XML文檔里創(chuàng)建超鏈接的標(biāo)準(zhǔn)。

If you want to learn more about XLink and XPointer, please visit our XLink and XPointer tutorial.
在我們的XLink / XPointer教程中，你可以學(xué)習(xí)與 XLink 和 XPointer 相關(guān)的更多內(nèi)容。

XQuery 1.0 and XPath 2.0 share the same data model and support the same functions and operators.
XQuery 1.0 和 XPath 2.0擁有同樣的數(shù)據(jù)模式并支持相同的函數(shù)和操作。

XQuery Functions
XQuery函數(shù)

XQuery is built on XPath expressions. XQuery 1.0 and XPath 2.0 share the same data model and support the same functions and operators.
XQuery 是建立在 XPath 表達(dá)式的基礎(chǔ)上的。XQuery 1.0 和 XPath 2.0 包含相同的數(shù)據(jù)模型并支持相同的函數(shù)和操作符。

XPath Operators
XPath 操作符

XPath Functions
XPath 函數(shù)

XQuery Data Types
XQuery 數(shù)據(jù)類型

XQuery shares the same data types as XML Schema 1.0 (XSD).
XQuery 和 XML Schema 1.0 (XSD) 包含了相同的數(shù)據(jù)類型。

XSD String
XSD 字符串

XSD Date
XSD 日期

XSD Numeric
XSD 數(shù)字

XSD Misc
XSD 混合數(shù)據(jù)類型

posted on 2007-12-13 14:26 gembin 閱讀(1869) 評(píng)論(0) 編輯收藏

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XQuery 語法

What is XQuery? 什么是XQuery？

XQuery is About Querying XML XQuery 是用于查詢XML的

XQuery and XPath XQuery 和 XPath

XQuery - Examples of Use XQuery —— 使用案例

XQuery is Not (Yet) a Web Standard XQuery 并不是網(wǎng)絡(luò)標(biāo)準(zhǔn)

The XML Example Document XML 案例文檔

How to Select Nodes From "books.xml"? 如何從"books.xml"文件中選擇節(jié)點(diǎn)？

Functions 函數(shù)

Path Expressions 路徑表達(dá)式

Predicates 條件謂語項(xiàng)

The XML Example Document XML 案例文檔

How to Select Nodes From "books.xml" With FLWOR 怎樣使用FLWOR表達(dá)式從"books.xml"文件中選擇節(jié)點(diǎn)

The XML Example Document XML 案例文檔

Present the Result In an HTML List 在HTML列表中顯示結(jié)果

XQuery 術(shù)語

Nodes 節(jié)點(diǎn)

Atomic values “原子值”屬性值

Items 項(xiàng)

Relationship of Nodes 節(jié)點(diǎn)間關(guān)系

Parent 父類

Children 子類元素

Siblings 同類元素

Ancestors 祖類元素

Descendants 孫類元素

XQuery Basic Syntax Rules XQuery 的基本語法規(guī)則

XQuery Conditional Expressions XQuery 的條件表達(dá)式

XQuery Comparisons XQuery 比較

The XML Example Document XML 案例文檔

Adding Elements and Attributes to the Result 向結(jié)果中添加元素和屬性

Add HTML Elements and Text 添加 HTML 元素和文本

Add Attributes to HTML Elements 向HTML元素中添加屬性

Selecting and Filtering Elements 選擇和過濾元素

The for Clause For 子句

XQuery Functions XQuery 函數(shù)

XQuery Built-in Functions XQuery 內(nèi)置函數(shù)

Examples of Function Calls 函數(shù)調(diào)用實(shí)例

XQuery User-Defined Functions XQuery 用戶自定義函數(shù)

Syntax 語法

Example of a User-defined Function Declared in the Query 在查詢語句里聲明的用戶自定義函數(shù)案例

XQuery Summary XQuery 概要

Now You Know XQuery, What's Next? 學(xué)會(huì)了XQuery，接下來該學(xué)些什么呢？

XQuery Functions XQuery函數(shù)

XQuery Data Types XQuery 數(shù)據(jù)類型

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What is XQuery?
什么是XQuery？

XQuery is About Querying XML
XQuery 是用于查詢XML的

XQuery and XPath
XQuery 和 XPath

XQuery - Examples of Use
XQuery —— 使用案例

XQuery is Not (Yet) a Web Standard
XQuery 并不是網(wǎng)絡(luò)標(biāo)準(zhǔn)

The XML Example Document
XML 案例文檔

How to Select Nodes From "books.xml"?
如何從"books.xml"文件中選擇節(jié)點(diǎn)？

Functions
函數(shù)

Path Expressions
路徑表達(dá)式

Predicates
條件謂語項(xiàng)

The XML Example Document
XML 案例文檔

How to Select Nodes From "books.xml" With FLWOR
怎樣使用FLWOR表達(dá)式從"books.xml"文件中選擇節(jié)點(diǎn)

The XML Example Document
XML 案例文檔

Present the Result In an HTML List
在HTML列表中顯示結(jié)果

Nodes
節(jié)點(diǎn)

Atomic values
“原子值”屬性值

Items
項(xiàng)

Relationship of Nodes
節(jié)點(diǎn)間關(guān)系

Parent
父類

Children
子類元素

Siblings
同類元素

Ancestors
祖類元素

Descendants
孫類元素

XQuery Basic Syntax Rules
XQuery 的基本語法規(guī)則

XQuery Conditional Expressions
XQuery 的條件表達(dá)式

XQuery Comparisons
XQuery 比較

The XML Example Document
XML 案例文檔

Adding Elements and Attributes to the Result
向結(jié)果中添加元素和屬性

Add HTML Elements and Text
添加 HTML 元素和文本

Add Attributes to HTML Elements
向HTML元素中添加屬性

Selecting and Filtering Elements
選擇和過濾元素

The for Clause
For 子句

XQuery Functions
XQuery 函數(shù)

XQuery Built-in Functions
XQuery 內(nèi)置函數(shù)

Examples of Function Calls
函數(shù)調(diào)用實(shí)例

XQuery User-Defined Functions
XQuery 用戶自定義函數(shù)

Syntax
語法

Example of a User-defined Function Declared in the Query
在查詢語句里聲明的用戶自定義函數(shù)案例

XQuery Summary
XQuery 概要

Now You Know XQuery, What's Next?
學(xué)會(huì)了XQuery，接下來該學(xué)些什么呢？

XQuery Functions
XQuery函數(shù)

XQuery Data Types
XQuery 數(shù)據(jù)類型