如何删除XQuery中的重复节点？ [英] How can I remove duplicate nodes in XQuery?

问题描述

我的函数看起来像：

  declare function local：start2（）{
 let $ data：= local：scan_books（）
 return<书籍> {$数据}< /书籍> 
}; 
  

示例输出是：

 <书籍> 
< book> 
< title> XML在24小时< / title> 
< author> Some Guy< / author> 
< / book> 
< book> 
< title> XML在24小时< / title> 
< author> Some Guy< / author> 
< / book> 
< / books> 
  

我只想在我的书籍根标记中输入一个条目，还有其他标签，如说小册子在那里也需要删除重复。任何想法？

---

更新了以下评论。通过唯一节点，我的意思是删除多个具有完全相同内容和结构的节点。

解决方案

更简单和更直接的一线XPath解决方案：

只需使用以下XPath表达式：

  / * / book 
 [index / of（/ * / book / title，
 title 
）
 [1] 
] 
  

应用于例如以下XML文件

：

 < books> 
< book> 
< title> XML在24小时< / title> 
< author> Some Guy< / author> 
< / book> 
< book> 
< title>西雅图食品< / title> 
< author> Some Guy2< / author> 
< / book> 
< book> 
< title> XML在24小时< / title> 
< author> Some Guy< / author> 
< / book> 
< book> 
< title>西雅图食品< / title> 
< author> Some Guy2< / author> 
< / book> 
< book> 
< title>如何解决XPAth问题< / title> 
< author> Me< / author> 
< / book> 
< / books> 
  

上述XPath表达式正确选择以下节点：

 < book> 
< title> XML在24小时< / title> 
< author> Some Guy< / author> 
< / book> 
< book> 
< title>西雅图食品< / title> 
< author> Some Guy2< / author> 
< / book> 
< book> 
< title>如何解决XPAth问题< / title> 
< author> Me< / author> 
< / book> 
  

解释很简单：对于每个书，仅选择其中一个出现 - 使其全书中的索引与标题在全部标题。

I have an XML document I generate on the fly, and I need a function to eliminate any duplicate nodes from it.

My function looks like:

declare function local:start2() {
    let $data := local:scan_books()
    return <books>{$data}</books>
};

Sample output is:

<books>
  <book>
    <title>XML in 24 hours</title>
    <author>Some Guy</author>  
  </book>
  <book>
    <title>XML in 24 hours</title>
    <author>Some Guy</author>  
  </book>
</books>

I want just the one entry in my books root tag, and there are other tags, like say pamphlet in there too that need to have duplicates removed. Any ideas?

---

Updated following comments. By unique nodes, I mean remove multiple occurrences of nodes that have the exact same content and structure.

解决方案

A simpler and more direct one-liner XPath solution:

Just use the following XPath expression:

  /*/book
        [index-of(/*/book/title, 
                  title
                 )
                  [1]
        ]

When applied, for example, on the following XML document:

<books>
    <book>
        <title>XML in 24 hours</title>
        <author>Some Guy</author>
    </book>
    <book>
        <title>Food in Seattle</title>
        <author>Some Guy2</author>
    </book>
    <book>
        <title>XML in 24 hours</title>
        <author>Some Guy</author>
    </book>
    <book>
        <title>Food in Seattle</title>
        <author>Some Guy2</author>
    </book>
    <book>
        <title>How to solve XPAth Problems</title>
        <author>Me</author>
    </book>
</books>

the above XPath expression selects correctly the following nodes:

<book>
    <title>XML in 24 hours</title>
    <author>Some Guy</author>
</book>
<book>
    <title>Food in Seattle</title>
    <author>Some Guy2</author>
</book>
<book>
    <title>How to solve XPAth Problems</title>
    <author>Me</author>
</book>

The explanation is simple: For every book, select only one of its occurences -- such that its index in all-books is the same as the first index of its title in all-titles.

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