UPDATE valid_time_table [ FOR PORTION OF valid_time_period_name FROM point_in_time_1 TO point_in_time_2 ] SET set_clause_list [ WHERE search_condition ] [;]
UPDATE valid_time_table [ FOR PORTION OF valid_time_period_name FROM point_in_time_1 TO point_in_time_2 ] SET set_clause_list [ WHERE search_condition ] [;]