It is straightforward to load GPX files (GPS downloaded tracks / points) into QGIS, then save and manipulate them as shapefiles. However, the recording date (in the comment (cmt) field) of waypoints is in the format
YY-MMM-DD HH:MM:SS (e.g. 28-AUG-11 11:57:51) and it would be possible to sort by date only if the format could be parsed to something closer to the ISO 8601 standard (YYYY-MM-DD ...).
String manipulation in the field calculator can take you partway:
'20' || substr(cmt,8,2) || '-' || substr(cmt, 4, 3) || '-' || substr(cmt, 1, 2) || ' ' || substr(cmt, 11, 8)
However, you're then left with
YYY-MMM-DD HH:MM:SS - i.e. AUG instead of 08.
Is there a straightforward way to parse the date string directly, providing integer months? (Ideally, something like the R strptime() function)