Fix obvious bug in nested selection.

Author: solidsnack

graphql.sql

@@ -305,17 +305,17 @@ BEGIN
       IF sub.body IS NOT NULL THEN                 -- TODO: Nested JSON lookups
         RAISE EXCEPTION 'Nested JSON lookup is as yet unimplemented';
       END IF;
-      lookups := lookups || format('->%L', sub.selector);
+      lookups := lookups || format('%I->%L', selector, sub.selector);
     WHEN regtype('hstore') THEN
       IF sub.body IS NOT NULL THEN
         RAISE EXCEPTION 'No fields below this level (column % is hstore)',
                         tab, col;
       END IF;
-      lookups := lookups || format('->%L', sub.selector);
+      lookups := lookups || format('%I->%L', selector, sub.selector);
     ELSE
       --- Treat it as a field lookup in a nested record (this could also end up
       --- being a function call, by the way).
-      lookups := lookups || format('.%I', sub.selector);
+      lookups := lookups || format('%I.%I', selector, sub.selector);
     END CASE;
     labels := labels || format('%I', sub.selector);
   END LOOP;