oracle 11g 删除所有表和视图

BEGIN
FOR i IN (SELECT us.sequence_name
FROM USER_SEQUENCES us) LOOP
EXECUTE IMMEDIATE 'drop sequence '|| i.sequence_name ||'';
END LOOP;
FOR i IN (SELECT ut.table_name
FROM USER_TABLES ut) LOOP
EXECUTE IMMEDIATE 'drop table '|| i.table_name ||' CASCADE CONSTRAINTS ';
END LOOP;
FOR i IN (SELECT view_name FROM user_views) loop
EXECUTE IMMEDIATE 'drop view ' || i.view_name;
END loop;
END;