BaseX XQUERY 选择具有特定属性值的节点

Question

XML sample:

    <mondial>
        <continent id="f0_119" name="Europe"/>
        <continent id="f0_123" name="Asia"/>
        <continent id="f0_126" name="America"/>
        <continent id="f0_129" name="Australia/Oceania"/>
        <continent id="f0_132" name="Africa"/>
        <country id="f0_136" name="Albania" capital="f0_1461" population="3249136"
                 datacode="AL" total_area="28750" population_growth="1.34"
                 infant_mortality="49.2" gdp_agri="55" gdp_total="4100"
                 inflation="16" indep_date="28 11 1912"
                 government="emerging democracy" car_code="AL">
            <name>Albania</name>
            <city id="f0_1461" country="f0_136" longitude="10.7" latitude="46.2">
                <name>Tirane</name>
                <population year="87">192000</population>
            </city>
            <city id="f0_36498" country="f0_136" longitude="19.2" latitude="42.2">
                <name>Shkoder</name>
                <population year="87">62000</population>
                <located_at type="lake" water="f0_39058"/>
            </city>
        </country>
    </mondial>

for $x in //mondial/country/population
where $x/@year=87
return $x/name

I'm basically trying to return <name> from the node <population> that has the attribute of year=87 . I know it sounds confusing as heck, I can't even find documentation for this I've tried googling how to select using the attribute but I can't seem to return anything.

Answer 1

Please try the following XQuery.

XQuery

for $x in //mondial/country/city
where $x/population/@year=87
return $x/name

Answer 2

Please note that the population elements in your XML document are children of the city elements. Next, you tried to loop over the population elements, and it's better to move this path step into the where clause. One solution for returning the city names is as follows:

for $city in /mondial/country/city
where $city/population/@year = 87
return $city/name

Answer 3

You can get to the required information with a single XPath

//city[population/@year=87]/name

Live Demo (xqueryfiddle)