基于排序顺序的不同元素

Question

我想要基于降序的书的明确标题 参考MarkLogic: XQuery to Get Distinct Names from XML Document?

<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>

代码

 let $result := 
     for $x at $i in doc("bookstore.xml")/bookstore/book/*
     order by $x/price descending
     return name($x)
  return fn:distinct-values($result)

Answer 1

如果您使用

distinct-values(
  for $book in bookstore/book
  order by $book/price descending
  return $book/title
)

你得到了

XQuery Kick Start
Learning XML
Everyday Italian
Harry Potter