| (: XQuery Aggregate Query :) | |
| (: Find the annual precipitation (PRCP) for a Seattle using the airport :) | |
| (: station (US000000002) for 2002. :) | |
| fn:count( | |
| let $collection := "ghcnd_half_1|ghcnd_half_2" | |
| for $r in collection($collection)/dataCollection/data | |
| where $r/station eq "GHCND:US000000002" | |
| and $r/dataType eq "PRCP" | |
| and fn:year-from-dateTime(xs:dateTime(fn:data($r/date))) eq 2002 | |
| return $r/value | |
| ) |