创建对象表的时候怎么抱错啊~！

[qqws]

create or replace type stu_sel_type as object(
class_name varchar2(50),class_cj varchar2(50))
--创建一个对象类型
/

create type stu_cla_type as table of stu_sel_type;
--创建一个嵌套表类型

create table student(stu stu_cla_type);
--创建表

为什么会报ORA-22913: 必须指定嵌套表列或属性的表名称 的错误啊，请高手指教

[qqws]

应该怎么改啊

[w_tsinghua]

给你一个例子：
CREATE TYPE Course AS OBJECT (
course_no NUMBER(4),
title VARCHAR2(35),
credits NUMBER(1));

CREATE TYPE CourseList AS TABLE OF Course;

CREATE TABLE department (
name VARCHAR2(20),
director VARCHAR2(20),
office VARCHAR2(20),
courses CourseList)
NESTED TABLE courses STORE AS courses_tab;