code: def sanity_updates_after_move(self, oldpath, newpath):
          
          if (
                  self.node_cls.get_database_vendor('write') == 'mysql' and
                  len(oldpath) != len(newpath)
          ):
              # no words can describe how dumb mysql is
              # we must update the depth of the branch in a different query
              self.stmts.append(
                  self.get_mysql_update_depth_in_branch(newpath))
  
          oldparentpath = self.node_cls._get_parent_path_from_path(oldpath)
          newparentpath = self.node_cls._get_parent_path_from_path(newpath)
          if (
                  (not oldparentpath and newparentpath) or
                  (oldparentpath and not newparentpath) or
                  (oldparentpath != newparentpath)
          ):
              # node changed parent, updating count
              if oldparentpath:
                  self.stmts.append(
                      self.get_sql_update_numchild(oldparentpath, 'dec'))
              if newparentpath:
                  self.stmts.append(
                      self.get_sql_update_numchild(newparentpath, 'inc'))
docs: Updates the list of sql statements needed after moving nodes.
  
          1. :attr:`depth` updates *ONLY* needed by mysql databases (*sigh*)
          2. update the number of children of parent nodes