SQL2005设外键问题，求帮助

[qq243803]

创建一个表的同时以自己的一个属性做外键该怎么写啊，我这样写为什么有问题
CREATE TABLE Course
(Cno CHAR(4) PRIMARY KEY,
Cname CHAR(40),
Cpno CHAR(4),
Ccredit SMALLINT,
FOREIGN KEY Cpno REFERENCES Course(Cno)
);

[sql2015]

CREATE TABLE Course(
	Cno CHAR(4) PRIMARY KEY,
	Cname CHAR(40),
	Cpno CHAR(4),
	Ccredit SMALLINT 
);

ALTER TABLE Course ADD CONSTRAINT
	FK_Course_Course FOREIGN KEY
	(
		Cpno
	) REFERENCES dbo.Course
	(
		Cno
	) 
	ON UPDATE  NO ACTION 
	ON DELETE  NO ACTION 

[极品老土豆]

CREATE TABLE Course
(Cno CHAR(4) PRIMARY KEY,
Cname CHAR(40),
Cpno CHAR(4) FOREIGN KEY  REFERENCES Course(Cno),
Ccredit SMALLINT
);