XQuery作业求助：获取人口增幅最大及最小的大洲数据

嘿，你这作业已经快收尾啦！既然已经把各洲的人口数据都存在$minAndMaxCont变量里了，那提取增幅最大和最小的大洲其实很容易，用XQuery的聚合函数就能搞定。

核心思路 #

注意@increase属性默认是字符串类型，所以第一步要把它转换成数值类型，再用max()和min()函数定位到极值，最后匹配对应的<Continent>元素即可。

具体代码实现 #

1. 获取增幅最大的大洲：

let $max_increase_continent := 
    $minAndMaxCont/Continent[number(@increase) = max($minAndMaxCont/Continent/number(@increase))]
return $max_increase_continent

2. 获取增幅最小的大洲：

let $min_increase_continent := 
    $minAndMaxCont/Continent[number(@increase) = min($minAndMaxCont/Continent/number(@increase))]
return $min_increase_continent

3. 如果需要一次性输出两者的结构化信息，合并代码更高效：

let $max_cont := $minAndMaxCont/Continent[number(@increase) = max($minAndMaxCont/Continent/number(@increase))]
let $min_cont := $minAndMaxCont/Continent[number(@increase) = min($minAndMaxCont/Continent/number(@increase))]
return
    <PopulationResult>
        <HighestIncrease>
            <ContinentName>{$max_cont/@name}</ContinentName>
            <CurrentPopulation>{$max_cont/@pop}</CurrentPopulation>
            <FuturePopulation>{$max_cont/@futurePop}</FuturePopulation>
            <TotalIncrease>{$max_cont/@increase}</TotalIncrease>
            <IncreaseRatio>{$max_cont/@ratio}</IncreaseRatio>
        </HighestIncrease>
        <LowestIncrease>
            <ContinentName>{$min_cont/@name}</ContinentName>
            <CurrentPopulation>{$min_cont/@pop}</CurrentPopulation>
            <FuturePopulation>{$min_cont/@futurePop}</FuturePopulation>
            <TotalIncrease>{$min_cont/@increase}</TotalIncrease>
            <IncreaseRatio>{$min_cont/@ratio}</IncreaseRatio>
        </LowestIncrease>
    </PopulationResult>

这段代码不仅能精准筛选出目标大洲，还会把关键数据整理成更清晰的结构输出，完全贴合作业要求~

内容的提问来源于stack exchange，提问作者Augman