xml - 使用 xquery FLWOR 表达式查找多个 "where"限制

Question

我正在尝试寻找在休斯顿从事项目工作的员工，但该项目所在的部门不在休斯顿。我试图在 this 之后对表达式进行建模FLWOR 表达式的示例，但查询不返回任何内容，它应该返回结果。

编辑:这里是 input .

xquery
let $doc := doc("~path/company.xml")
for $e in $doc//employee,
    $d in $doc//department,
    $p in $doc//projects
where $d/locations[location!="Houston"]
and $p/project[plocations="Houston"]
return <e>{$e/fname}{$e/lname}{$e/address}</e>
/

Answer 1

一个for子句就足够了；否则，您将多次遍历所有员工:

let   $doc := doc(...)
for   $e in $doc//employee
let   $p := $doc//project[@pnumber = $e/projects/worksOn/@pno]
where $p[plocation = 'Houston']
  and $doc//department[@dno = $p/@controllingDepartment]
                      [not(locations/location = 'Houston')]
return <e>{ $e/fname }{ $e/lname }{ $e/address }</e>