Question

对于下面的XML数据，我试图得到这里显示的输出：即我想看到人口超过20000的国家的名称，条件是显示的城市数量应仅适用于那些人口超过3500.此外，对于一些国家，这个城市在一个省内。

<result>
  <country name="B">
    <num_cities>3</num_cities>
  </country>
  <country name="C">
    <num_cities>2</num_cities>
  </country>
</result>

---------------------------这是XML数据--------------- -------

<country id="1" name="A" population="12000">
   <name>A</name>
   <city id="c1" country="1">
      <name>T1</name>
      <population>5000</population>
   </city>
   <city id="c2" country="1">
      <name>T2</name>
      <population>3000</population>
   </city>
   <city id="c3" country="1">
      <name>T3</name>
      <population>4000</population>
   </city>
</country>
<country id="3" name="B" population="80000">
   <name>B</name>
   <city id="c4" country="2">
      <name>T4</name>
      <population>6000</population>
   </city>
   <city id="c5" country="2">
      <name>T5</name>
      <population>2000</population>
   </city>
   <city id="c6" country="2">
      <name>T6</name>
      <population>60000</population>
   </city>
   <city id="c7" country="2">
      <name>T7</name>
      <population>12000</population>
   </city>
</country>
<country id="3" name="C" population="68000">
   <name>C</name>
   <province>P1</province>
   <city id="c8" country="3">
      <name>T8</name>
      <population>51000</population>
   </city>
   <city id="c9" country="3">
      <name>T9</name>
      <population>3000</population>
   </city>
   <city id="c10" country="3">
      <name>T10</name>
      <population>14000</population>
   </city>
</country>

我写了这个xquery，但我不知道如何排除有人口的城市＆gt; 3500.我可能没有正确编写代码......请协助。

for $c in doc("abc")//country
let $city:= count($c/city/name)
let $citypr:= count($c/province/city/name)
where $c/@population>1000000
return
<result>
<country name='{data($c/name) }'></country>
 <num_of_cities>
 {
 if (exists ($c/city/name)) then
 $city
 else
 $citypr
}
 </num_of_cities>
</result>

Answer 1

一些提示：

请勿在检索内容的说明符中尽早使用where条款进行过滤。
如果你想只有一个<result>，而不是每个数据一个，你需要在之前启动FLWOR表达式;每件物品都会退回一次。

这是一个更接近的例子：

<result>{
  for $large-country in doc("abc")//country[@population > 20000]
  let $large-cities := $country/city[population > 3500]
  return
    <country name="{$large-country/@name}">
      <num_cities>{count($large-cities)}</num_cities>
    </country>
}</result>

人口数据xquery

1 个答案: