Question

我是XQuery的新手，我的问题是关于不同的值，我使用以下代码来检索电影评论者

xquery version "1.0";
declare boundary-space preserve;
<result>
{for $reviews in doc("reviews.xml")/reviews/review,
     $movie in doc("movies.xml")/movies/movie
 where $reviews/movie_title = $movie/movie_title
   and $movie//movie_genre = "Drama"
   and $movie//month > 6
 order by $reviews/movie_reviewer descending
 return
(<reviewer>{distinct-values($reviews/movie_reviewer)}</reviewer>, '&#xa;')
 }
 </result>

以后我将代码更改为

xquery version "1.0";
declare boundary-space preserve;
<result>
{for $reviews in doc("reviews.xml")/reviews/review,
     $movie in doc("movies.xml")/movies/movie
 where $reviews/movie_title = $movie/movie_title
   and $movie//movie_genre = "Drama"
   and $movie//month > 6
 return
{for $content in distinct-values($reviews/movie_reviewer)
      order by $content descending
      return (<reviewer>{$content}</reviewer>, '&#xa;')}
 }
 </result>

但我得到的结果与

相似

 <result>
 <reviewer>Wesley Barry</reviewer>
 <reviewer>Michael Gordon</reviewer>
 <reviewer>Michael Gordon</reviewer>
 <reviewer>Michael Gordon</reviewer>
 <reviewer>John Frankenheimer</reviewer>
 <reviewer>J. Lee Thompson</reviewer>
 <reviewer>J. Lee Thompson</reviewer>
 <reviewer>Charles Walters</reviewer>
 <reviewer>Charles Walters</reviewer>
 </result>

我怎样才能使结果像

一样

<result>
 <reviewer>Wesley Barry</reviewer>
 <reviewer>Michael Gordon</reviewer>
 <reviewer>John Frankenheimer</reviewer>
 <reviewer>J. Lee Thompson</reviewer>
 <reviewer>Charles Walters</reviewer>
 </result>

？我知道这是非常基本的，但我不能明白这一点

Answer 1

请关注@ Ranon的建议。但是，从您的查询中猜测：最简单的方法是使用XQuery 3.0和新的逐个语句。

xquery version "3.0";
declare boundary-space preserve;
<result>
{for $reviews in doc("reviews.xml")/reviews/review,
     $movie in doc("movies.xml")/movies/movie
 let $reviewer := $reviews/movie_reviewer
 where $reviews/movie_title = $movie/movie_title
   and $movie//movie_genre = "Drama"
   and $movie//month > 6
 group by $reviewer
 order by $reviewer descending
 return
(<reviewer>{$reviewer}</reviewer>, '&#xa;')
 }
 </result>

distinct-values（）返回结果不起作用？

1 个答案: