| (: XQuery Join Aggregate Query :) | |
| (: Count all sensor readings for TMIN in 2001. :) | |
| count( | |
| let $sensor_collection := "../../../../../../../weather_data/dataset-tiny-local/data_links/local_speed_up/d0_p1_i0/sensors/?select=*.xml;recurse=yes" | |
| for $r in collection($sensor_collection)/root/dataCollection/data | |
| let $date := xs:date(fn:substring(xs:string(fn:data($r/date)), 0, 11)) | |
| where $r/dataType eq "TMIN" | |
| and fn:year-from-date($date) eq 2001 | |
| return $r/value | |
| ) |