7.1һͼѧϢѧѧţ༶ѧϰɼиѧĿγ̺źͳɼҳɼ90
	CREATE  VIEW  V_chengji
	AS
	SELECT  student.sName, student.sID, student.sSex, student.sBanji, grade.kcID, grade.gradeNum
	FROM  student CROSS JOIN grade
	WHERE (grade.gradeNum > 90)
7.2޸ǰ洴ͼһרҵ
	ALTER  VIEW  V_chengji
	AS
	SELECT  student.sName, student.sID, student.sSex, student.sZhuanye,
                student.sBanji,grade.kcID, grade.gradeNum
	FROM  student CROSS JOIN grade
	WHERE (grade.gradeNum > 90)
7.3洴V_chengjiͼɾ
	DROP  VIEW  v_chengji 
TEACHERУڽʦţtIDPRIMARY KEYԼPK_ Teacher_idͨ˷ʵΪ	PK_Teacher_Teacher_id
	ALTER TABLE Teacher  WITH NOCHECK
	ADD CONSTRAINT PK_Teacher_id PRIMARY KEY (tID)
7.4γϢпγ̱дΪۼ
	CREATE CLUSTERED INDEX  IX_ Course
	    ON Course (kcID) 
7.5Ϊ༶Ϣеİ༶дΨһķǾۼǿƲеݾΨһԣ֤˰༶Ʋ
	CREATE UNIQUE INDEX AK_ Class
	    ON Classe(ClsName)
7.6ΪѧϰɼѧźͿγ̺ϴǾۼ
	CREATE NONCLUSTERED INDEX IX_grade
	    ON grade(sID,kcID)
7.7ɾ7.4
	DROP INDEX IX_ Course ON Course
