xQuery更新问题

Question

这是我的xml

<book asin="0201100886"
  created="128135928"
  lastLookupTime="128135928">
  <price>102.00</price>
  <purchaseDate>2005-01-22</purchaseDate>
</book>

<book asin="0122513363" created="128135600" lastLookupTime="128136224">
  <price>50.95</price>
  <purchaseDate>2005-01-22</purchaseDate>
</book>

<book asin="0201441241"
  created="128136896"
  lastLookupTime="128136896">
  <price>108.20</price>
  <purchaseDate>2005-01-22</purchaseDate>
</book>


<book asin="0471250600"
  created="128136896"
  lastLookupTime="128136896">
  <price>107.95</price>
  <purchaseDate>2005-01-22</purchaseDate>
</book>

<book asin="0321193628"
  created="128136896"
  lastLookupTime="128136896">
  <price>112.40</price>
</book>

我需要将所有图书价格更新0.50美分。我怎么能这样做？

Answer 1

如果您正在寻找使用XQuery Update Facility的解决方案：

for $p in //price return
replace value of node $p with $p + 0.50

Answer 2

在XQuery中，使用递归函数进行转换。

declare function local:reprice($nodes as node()*) {
  for $node in $nodes
  return
    typeswitch($node)
       case element(price)
          return element price {xs:decimal($node) + 0.5}
       case element(
          return 
            element {name($node)} {
               $node/@*,
               local:reprice($node/node())}
      default
        return $node
 };

然后如果图书文档被引用为$ books：

local:reprice($books)

进一步的讨论和例子在http://en.wikibooks.org/wiki/XQuery/Typeswitch_Transformations中。

或者，使用XML数据库，例如eXist-db和更新insitu：

 for $price in $books//price
 let $newprice := xs:decimal($price) + 0.5
 return update replace $price with elememt price {$newprice}

请注意，在更广泛支持XQuery Update之前，XQuery更新扩展主要依赖于实现

Answer 3

XSLT比XQuery更适合用于此类任务：

此转化：

<xsl:stylesheet version="1.0"
 xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
 <xsl:output omit-xml-declaration="yes" indent="yes"/>
 <xsl:strip-space elements="*"/>


 <xsl:template match="node()|@*">
  <xsl:copy>
   <xsl:apply-templates select="node()|@*"/>
  </xsl:copy>
 </xsl:template>

 <xsl:template match="price/text()">
  <xsl:value-of select="format-number(. + 0.50, '##0.00')"/>
 </xsl:template>
</xsl:stylesheet>

应用于提供的XML文档：

<books>
    <book asin="0201100886"   created="128135928"   lastLookupTime="128135928">
        <price>102.00</price>
        <purchaseDate>2005-01-22</purchaseDate>
    </book>
    <book asin="0122513363" created="128135600" lastLookupTime="128136224">
        <price>50.95</price>
        <purchaseDate>2005-01-22</purchaseDate>
    </book>
    <book asin="0201441241"   created="128136896"   lastLookupTime="128136896">
        <price>108.20</price>
        <purchaseDate>2005-01-22</purchaseDate>
    </book>
    <book asin="0471250600"   created="128136896"   lastLookupTime="128136896">
        <price>107.95</price>
        <purchaseDate>2005-01-22</purchaseDate>
    </book>
    <book asin="0321193628"   created="128136896"   lastLookupTime="128136896">
        <price>112.40</price>
    </book>
</books>

生成想要的正确结果：

<books>
   <book asin="0201100886" created="128135928" lastLookupTime="128135928">
      <price>102.50</price>
      <purchaseDate>2005-01-22</purchaseDate>
   </book>
   <book asin="0122513363" created="128135600" lastLookupTime="128136224">
      <price>51.45</price>
      <purchaseDate>2005-01-22</purchaseDate>
   </book>
   <book asin="0201441241" created="128136896" lastLookupTime="128136896">
      <price>108.70</price>
      <purchaseDate>2005-01-22</purchaseDate>
   </book>
   <book asin="0471250600" created="128136896" lastLookupTime="128136896">
      <price>108.45</price>
      <purchaseDate>2005-01-22</purchaseDate>
   </book>
   <book asin="0321193628" created="128136896" lastLookupTime="128136896">
      <price>112.90</price>
   </book>
</books>