如何让 XQuery 提取 XML 文档中的所有匹配节点

Question

我是 XQuery 的新手，知道这可能是一个简单的答案，但我就是无法理解这个问题。

我有一个 XML 文件，如下所示：

<EventLog>
  <SongSet>
    <Song SongID="S002">
      <Title>Band on the Run</Title>
      <Composer>Paul McCartney</Composer>
      <Duration>1.15</Duration>
    </Song>
    <Song SongID="S003">
      <Title>Come on Over</Title>
      <Composer>Shania Twain</Composer>
      <Duration>3.15</Duration>
    </Song>
   </SongSet>
  <ContestantSet>
   <Contestant Name="Randy Stuss" Hometown="Ottawa">
      <Repertoire>
        <SongRef>S002</SongRef>
        <SongRef>S003</SongRef>
      </Repertoire>
     </Contestant>
     <Contestant Name="Fletcher Gee" Hometown="Toronto">
      <Repertoire>
        <SongRef>S002</SongRef>
        <SongRef>S003</SongRef>
      </Repertoire>
    </Contestant>
  </ContestantSet>
</EventLog>

我需要这样的输出：

<songs> 
  <song> 
    <name> SONG NAME1 </name>
    <composer> COMPOSER NAME </composer>
    <singers>
      <singer>Singer1 Name  </singer>  
      <singer>Singer2 Name  </singer>  
    </singers>
  </song>
<songs>

除了把歌手的名字放在一起，我可以做所有的事情。我的输出如下所示：

<Songs
  <Song>
    <Title>Band on the Run</Title>
    <Composer>Paul McCartney</Composer>
    <Singers>
      <Singer>Fletcher Gee</Singer>
    </Singers>
  </Song>
  <Song>
    <Title>Band on the Run</Title>
    <Composer>Paul McCartney</Composer>
  <Singers>
    <Singer>Randy Stuss</Singer>
  </Singers>
  </Song>
</Songs>

这是我的 XQuery 代码：

for $x in //SongSet/Song 
for $y in //ContestantSet/Contestant 
where $x/@SongID = $y/Repertoire/SongRef 
return <Song><Title>{data($x/Title)}</Title>
       <Composer>{data($x/Composer)}</Composer>
       <Singers><Singer>{data($y/@Name)}</Singer></Singers></Song>

我哪里错了？

感谢您的帮助！！！

Answer 1

一种可能的方式；遍历 <Song> 个元素，然后 return <Singers> 部分遍历匹配的 <Contestant> 个元素：

for $x in //SongSet/Song 
return <Song><Title>{data($x/Title)}</Title>
       <Composer>{data($x/Composer)}</Composer>
       <Singers>{for $y in //ContestantSet/Contestant[Repertoire/SongRef = $x/@SongID]
                 return <Singer>{data($y/@Name)}</Singer>}</Singers></Song>

Xpathtester Demo

当针对有问题的 XML 进行测试时，输出符合预期：

<?xml version="1.0" encoding="UTF-8"?>
<Song>
   <Title>Band on the Run</Title>
   <Composer>Paul McCartney</Composer>
   <Singers>
      <Singer>Randy Stuss</Singer>
      <Singer>Fletcher Gee</Singer>
   </Singers>
</Song>
<Song>
   <Title>Come on Over</Title>
   <Composer>Shania Twain</Composer>
   <Singers>
      <Singer>Randy Stuss</Singer>
      <Singer>Fletcher Gee</Singer>
   </Singers>
</Song>

如何让 XQuery 提取 XML 文档中的所有匹配节点

How do I get XQuery to extract all the matching nodes in an XML Document

xml

xquery