| (: XQuery Join Aggregate Query :) |
| (: Self join with all sensor readings after the year 2000. :) |
| fn:avg( |
| let $sensor_collection_min := "../../../../../../../weather_data/dataset-tiny-local/data_links/local_speed_up/d0_p1_i0/sensors/?select=*.xml;recurse=yes" |
| for $r_min in collection($sensor_collection_min)/root/dataCollection/data |
| |
| let $sensor_collection_max := "../../../../../../../weather_data/dataset-tiny-local/data_links/local_speed_up/d0_p1_i0/sensors/?select=*.xml;recurse=yes" |
| for $r_max in collection($sensor_collection_max)/root/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) |
| ) div 10 |
