如何在创建视图时同时创建一个在视图上面的约束

[七年]

如何在创建视图时同时创建一个在视图上面的约束
CREATE VIEW emp_sal (emp_id, last_name,
email UNIQUE RELY DISABLE NOVALIDATE,
CONSTRAINT id_pk PRIMARY KEY (emp_id) RELY DISABLE NOVALIDATE)
AS SELECT employee_id, last_name, email FROM employees;
该例摘自oracle 9i sql用户手册
我的sql语句为：
CREATE OR REPLACE VIEW dept20
(
EMPLOYEE_ID,EMPLOYEE, DEPARTMENT_ID,
CONSTRAINT ch CHECK (DEPARTMENT_ID = 20) RELY DISABLE NOVALIDATE
)
AS
SELECT empno ,ename ,deptno
FROM emp
WHERE deptno = 20
WITH CHECK OPTION CONSTRAINT ch/

CONSTRAINT ch CHECK (DEPARTMENT_ID = 20) RELY DISABLE NOVALIDATE
*
ERROR 位于第 3 行:
ORA-00904: 无效列名

未找到解决方法？

现象一：
CREATE OR REPLACE VIEW dept20
(
EMPLOYEE_ID,EMPLOYEE, DEPARTMENT_ID,
CONSTRAINT ch PRIMARY KEY (DEPARTMENT_ID) RELY DISABLE NOVALIDATE
)
AS
SELECT empno ,ename ,deptno
FROM emp
WHERE deptno = 20

该视图创建成功

[qiuyuwen]

只能在基表上创建约束。
视图上不能，可以通过创建视图的sql实现相同的功能。