CREATE TRIGGER "rtree_<t>_<c>_update6" AFTER UPDATE OF "<c>" ON "<t>"
  WHEN OLD."<i>" = NEW."<i>" AND
       (NEW."<c>" NOTNULL AND NOT ST_IsEmpty(NEW."<c>")) AND
       (OLD."<c>" NOTNULL AND NOT ST_IsEmpty(OLD."<c>"))
BEGIN
  UPDATE "rtree_<t>_<c>" SET
    minx = ST_MinX(NEW."<c>"),
    maxx = ST_MaxX(NEW."<c>"),
    miny = ST_MinY(NEW."<c>"),
    maxy = ST_MaxY(NEW."<c>")
  WHERE id = NEW."<i>";
END;