Question

我有这段代码

for $sea in distinct-values (doc("mondial.xml")//island/tokenize(@sea,"\s"))
let $count := count(doc("mondial.xml")//island[@sea = $sea]/tokenize(@sea,"\s"))
let $seacount := concat($sea," ",$count)
return $seacount

返回给我

“sea-ArcticOcean 3 sea-Greenlandsea 0 sea-NorwegianSea 1 sea-BarentsSea 0

sea-Atlantic 53 sea-LabradorSea 0 ...“等等。

数字是你可以看到$ count和sea-XXX部分是变量$ sea。我现在坚持的是以某种方式选择$ sea，它具有所有计数的最大值$ count并显示该海名。我尝试过将$ max变量添加到：

 for $sea in distinct-values (doc("mondial.xml")//island/tokenize(@sea,"\s"))
let $count := count(doc("mondial.xml")//island[@sea = $sea]/tokenize(@sea,"\s"))
let $seacount := concat($sea," ",$count)
$max := concat($sea," ",max($count))
return $max

还尝试通过$ count（descending）语句添加订单，然后返回第一个节点：

for $sea in distinct-values (doc("mondial.xml")//island/tokenize(@sea,"\s"))
let $count := count(doc("mondial.xml")//island[@sea = $sea]/tokenize(@sea,"\s"))
let $seacount := concat($sea," ",$count)
order by $count descending
return $seacount[1]

我是以错误的方式接近这个还是？

Answer 1

这将返回每个迭代的结果序列的第一个节点。在这种情况下，$seacount始终是1个字符串的序列，因此您始终选择等效的('sea-value count')[1]，这只是单个字符串值。要仅选择一个整体，将整个查询包装在parens中以创建所有迭代的所有值的序列，然后选择第一个：

(for $sea in distinct-values (doc("mondial.xml")//island/tokenize(@sea,"\s")) let $count := count(doc("mondial.xml")//island[@sea = $sea]/tokenize(@sea,"\s")) let $seacount := concat($sea," ",$count) order by $count descending return $seacount)[1]

如何从字符串中选择某些节点/单词

1 个答案: