| (: XQuery Join Aggregate Query :) |
| (: Find the lowest recorded temperature (TMIN) in the United States for :) |
| (: 2001. :) |
| let $station_collection := "ghcnd_half_1|ghcnd_half_2" |
| for $s in collection($station_collection)/stationCollection/station |
| |
| let $sensor_collection := "ghcnd_half_1|ghcnd_half_2" |
| for $r in collection($sensor_collection)/dataCollection/data |
| |
| where $s/id eq $r/station |
| and (some $x in $s/locationLabels satisfies ($x/type eq "CNTRY" and $x/id eq "FIPS:US")) |
| and $r/dataType eq "TMIN" |
| and fn:year-from-dateTime(xs:dateTime(fn:data($r/date))) eq 2001 |
| return $r/value |
