如何使用FLWOR对XML文件中的特定元素进行计数？

Question

我希望为下面的示例xml计算Orders中所有标记Order的总和。总和。

如何返回元素标签的数量foo？这里，一种计数是：

1
1

而我只想求和: 2。

查询：

for $i in doc("foo.xml")/windward-studios/Orders/Order
return count($i)

sample xml：

<windward-studios>
  <Orders>
    <Order OrderID="10248">
      <CustomerID>VINET</CustomerID>
      <EmployeeID>5</EmployeeID>
      <OrderDate>1996-07-04T14:25:55</OrderDate>
      <RequiredDate>1996-08-01T06:43:44</RequiredDate>
      <ShippedDate>1996-07-16T04:00:12</ShippedDate>
      <ShipVia>3</ShipVia>
      <Freight>32.3800</Freight>
      <ShipName>Vins et alcools Chevalier</ShipName>
      <ShipAddress>59 rue de l'Abbaye</ShipAddress>
      <ShipCity>Reims</ShipCity>
      <ShipRegion/>
      <ShipPostalCode>51100</ShipPostalCode>
      <ShipCountry>France</ShipCountry>
      <OrderDetails>
        <OrderDetail>
          <ProductID>11</ProductID>
          <UnitPrice>14.0000</UnitPrice>
          <Quantity>12</Quantity>
          <Discount>0</Discount>
        </OrderDetail>
        <OrderDetail>
          <ProductID>42</ProductID>
          <UnitPrice>9.8000</UnitPrice>
          <Quantity>10</Quantity>
          <Discount>0</Discount>
        </OrderDetail>
        <OrderDetail>
          <ProductID>72</ProductID>
          <UnitPrice>34.8000</UnitPrice>
          <Quantity>5</Quantity>
          <Discount>0</Discount>
        </OrderDetail>
      </OrderDetails>
    </Order>
    <Order OrderID="10249">
      <CustomerID>TOMSP</CustomerID>
      <EmployeeID>6</EmployeeID>
      <OrderDate>1996-07-05T06:39:18</OrderDate>
      <RequiredDate>1996-08-16T03:39:38</RequiredDate>
      <ShippedDate>1996-07-10T14:39:39</ShippedDate>
      <ShipVia>1</ShipVia>
      <Freight>11.6100</Freight>
      <ShipName>Toms Spezialitäten</ShipName>
      <ShipAddress>Luisenstr. 48</ShipAddress>
      <ShipCity>Münster</ShipCity>
      <ShipRegion/>
      <ShipPostalCode>44087</ShipPostalCode>
      <ShipCountry>Germany</ShipCountry>
      <OrderDetails>
        <OrderDetail>
          <ProductID>14</ProductID>
          <UnitPrice>18.6000</UnitPrice>
          <Quantity>9</Quantity>
          <Discount>0</Discount>
        </OrderDetail>
        <OrderDetail>
          <ProductID>51</ProductID>
          <UnitPrice>42.4000</UnitPrice>
          <Quantity>40</Quantity>
          <Discount>0</Discount>
        </OrderDetail>
      </OrderDetails>
    </Order>
  </Orders>
</windward-studios>

Answer 1

您迭代了每个Order元素，然后请求每个元素的计数。

相反，可以询问Order元素的数量：

let $orders := doc("foo.xml")/windward-studios/Orders/Order
return count($orders)

您可以在不使用FLWOR的情况下更简单地完成此操作：

count(doc("foo.xml")/windward-studios/Orders/Order)

Answer 2

邀请对以下内容发表评论：

for $x at $i in db:open("southwind")/windward-studios/Orders/Order
return $i

我发现这很有趣，因为索引可以用作属性。请参见：

https://www.w3schools.com/xml/xquery_select.asp