如何从字符串中选择某些nodes/words

Question

我有这个代码

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

哪个returns对我来说

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

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

数字就是$count，sea-XXX部分就是变量$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（降序）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]

我是不是用错了方法？

Answer 1

这将 return 结果序列的第一个节点 对于每个 迭代。在这种情况下，$seacount 始终是 1 个字符串的序列，因此您总是 selecting 等效于 ('sea-value count')[1]，这只是单一字符串值。为了 select 只有一个整体，将整个查询包装在括号中以创建所有迭代的所有值的序列，然后 select 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nodes/words

How to choose certain nodes/words from a string

string

xquery