XQuery 返回错误..? [英] XQuery returning an error..?

问题描述

下面是 XML 文件 -

<Continent n="亚洲"><国家 n="泰国"><城市><姓名>曼谷</姓名><泰国首都<</城市></国家><国家 n="印度"><城市><姓名>新德里</姓名><资本在印度</城市><城市><姓名>孟买</姓名><印度的金融资本</城市><城市><姓名>钦奈</姓名><一个非常好的城市<Desc></城市></国家></大陆></大陆>

使用 baseX，我正在编写查询以显示包含单词 Capital 的城市的 Name，但返回错误.查询是 -

/Continents/Continent[contains(Country/City/Desc,'Capital')]/Country/City/Name

错误是 -错误:[XPTY0004] 应为单个项目，(元素 Desc { ... }，元素 Desc { ... }, ...)找到.

请帮帮我.. 此类查询是否需要使用 FLWOR?

解决方案

您的原始查询可以改写如下...

/大陆/大陆[Country/City/Desc 中的一些 $x 满足 contains($x,'Capital')]/国家/城市/名称

...或...

/大陆/大陆[国家/城市/描述中的 $x其中包含($ x，'资本')返回 $x]/国家/城市/名称

...但两个查询都将返回任何大陆的所有国家，其中包含包含首都"的城市描述.相反，这可能是您正在寻找的:

/Continents/Continent/Country/City[contains(Desc,'Capital')]/Name

您也可以使用 contains text 表达式来忽略大小写、变音符号等. 用你的关键词:

/Continents/Continent/Country/City[Desc contains text 'Capital']/Name

希望这会有所帮助.

Below is the XML file -

<Continents>
  <Continent n="Asia">
    <Country n="Thailand">
      <City>
        <Name>Bangkok</Name>
        <Desc>Capital on Thailand</Desc>
      </City>
    </Country>
    <Country n="India">
      <City>
        <Name>New Delhi</Name>
        <Desc>Capital on India</Desc>
      </City>
      <City>
        <Name>Mumbai</Name>
        <Desc>Financial capital on India</Desc>
      </City>
      <City>
        <Name>Chennai</Name>
        <Desc>A very good city</Desc>
      </City>
    </Country>
  </Continent>
</Continents>

Using baseX, I am writing a query to display the Name of cities containing the word Capital but is returning error. The query is -

/Continents/Continent[contains(Country/City/Desc,'Capital')]/Country/City/Name

and the error is - Error: [XPTY0004] Single item expected, (element Desc { ... }, element Desc { ... }, ...) found.

Please help me out.. Is it required to use FLWOR for such queries?

解决方案

Your original query could have been rewritten as follows...

/Continents/Continent[
  some $x in Country/City/Desc satisfies contains($x,'Capital')]
  /Country/City/Name

...or...

/Continents/Continent[
  for $x in Country/City/Desc
  where contains($x,'Capital')
  return $x]/Country/City/Name

...but both of the queries will return all countries of any continent that contains a city description containing 'Capital'. Instead, this is probably what you are looking for:

/Continents/Continent/Country/City[contains(Desc,'Capital')]/Name

You may as well use the contains text expression to ignore case, diacritics, etc. in your key words:

/Continents/Continent/Country/City[Desc contains text 'Capital']/Name

Hope this helps.

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