Improve sort for Select

calculate/lib/datavars.py

@@ -1040,6 +1040,9 @@ class DataVars:
             res = filter(filterFunc,
                   zipVars(where,selField))
         if sort:
+            if "/" in sort:
+                sort,sortkey = sort.split('/')
+                sortkey = itemgetter(*map(int,sortkey.split(',')))
             res.sort(key=sortkey,reverse=True if sort == "DESC" else False)
         if limit == 1:
             if not any(res):