[英]XQuery get distinct values
Im new to XQuery and are trying to learn how to use it with BaseX.我是 XQuery 的新手,正在尝试学习如何将它与 BaseX 一起使用。
I have this xml containing multiple elements of program :我有这个 xml 包含程序的多个元素:
<program id="4565">
<name>Musiken i P3</name>
<url>http://sverigesradio.se/sida/default.aspx?programid=4565</url>
<editor>Anna-Karin Larsson</editor>
<channel>164</channel>
<category>5</category>
</program>
So far i have understod that i can get the distinct values of for example editor like such:到目前为止,我已经理解我可以获得例如编辑器的不同值,如下所示:
let $vals := $sr/sr/programs/program/editor
let $uniqe-items := distinct-values($vals)
for $vals in $uniqe-items
order by $vals
return <li>{string($vals)}</li>
However when i do this I only get the editors name and I can't understand how i also check something like this:然而,当我这样做时,我只得到编辑的名字,我不明白我是如何检查这样的:
let $vals := $sr/sr/programs/program/editor
let $uniqe-items := distinct-values($vals)
for $vals in $uniqe-items
where $vals/channel = "132"
order by $vals
return <li>{string($vals)}</li>
I was thinking that i could do something like $vals/../channel
to get back to the channel attribute but that doesn't seem to be the case.我在想我可以做一些类似
$vals/../channel
的事情来回到通道属性,但似乎并非如此。
Please try the following solution.请尝试以下解决方案。 I am using BaseX 9.5
我正在使用 BaseX 9.5
The distinct-values()
gives a sequence of strings: Anna-Karin Larsson, Anna Karenina, not the XML elements. distinct-values()
给出一个字符串序列:Anna-Karin Larsson、Anna Karenina,而不是 XML 元素。
It is possible to eliminate where
clause completely by using XPath predicate in the for
clause:在
for
子句中使用 XPath 谓词可以完全消除where
子句:
for $vals in distinct-values(./programs/program[channel = "132"]/editor)
XQuery XQuery
xquery version "3.1";
declare context item := document {
<programs>
<program id="4565">
<name>Musiken i P3</name>
<url>http://sverigesradio.se/sida/default.aspx?programid=4565</url>
<editor>Anna-Karin Larsson</editor>
<channel>164</channel>
<category>5</category>
</program>
<program id="4770">
<name>Musiken i P3</name>
<url>http://sverigesradio.se/sida/default.aspx?programid=4565</url>
<editor>Anna Karenina</editor>
<channel>132</channel>
<category>55</category>
</program>
</programs>
};
<ul>
{
for $vals in distinct-values(./programs/program[channel = "132"]/editor)
(:where ./programs/program[editor = $vals]/channel = "132":)
order by $vals
return <li>{data($vals)}</li>
}
</ul>
Output Output
<ul>
<li>Anna Karenina</li>
</ul>
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