| (: XQuery Self Join Query :) |
| (: Self join with all stations finding the difference in min and max :) |
| (: temperature and get the average. :) |
| fn:count( |
| let $sensor_collection_min := "ghcnd" |
| for $r_min in collection($sensor_collection_min)/dataCollection/data |
| |
| let $sensor_collection_max := "ghcnd" |
| for $r_max in collection($sensor_collection_max)/dataCollection/data |
| |
| where $r_min/station eq $r_max/station |
| and $r_min/date eq $r_max/date |
| and $r_min/dataType eq "TMIN" |
| and $r_max/dataType eq "TMAX" |
| return $r_max/value - $r_min/value |
| ) |
