CREATE TABLE Student	(
	stuId		VARCHAR2(6),
	lastName	VARCHAR2(20)  NOT NULL,
	firstName 	VARCHAR2(20)  NOT NULL,
	major		VARCHAR2(10),
	credits  	NUMBER(3) DEFAULT 0,
	CONSTRAINT Student_stuId_pk PRIMARY KEY (stuId),
CONSTRAINT Student_credits_cc CHECK ((credits>=0) AND (credits < 150))); 

CREATE TABLE Faculty	(
	facId		VARCHAR2(6),
	name	 	VARCHAR2(20)  NOT NULL,
	department	VARCHAR2(20),
	rank 		VARCHAR2(10),
	CONSTRAINT Faculty_facId_pk PRIMARY KEY (facId));

CREATE TABLE Class	(
	classNumber	VARCHAR2(8),
	facId	 	VARCHAR2(6)  NOT NULL,
	schedule  	VARCHAR2(8),
	room		VARCHAR2(6),
	CONSTRAINT Class_classNumber_pk PRIMARY KEY (classNumber),
CONSTRAINT Class_facId_fk FOREIGN KEY (facId) REFERENCES Faculty (facId) ON DELETE SET NULL,
CONSTRAINT Class_schedule_room_uk UNIQUE (schedule, room));

CREATE TABLE Enroll	(
	stuId		VARCHAR2(6),	
	classNumber	VARCHAR2(8),
	grade		VARCHAR2(2),
	CONSTRAINT Enroll_classNumber_stuId_pk PRIMARY KEY (classNumber, stuId),
CONSTRAINT Enroll_classNumber_fk FOREIGN KEY (classNumber) REFERENCES Class (classNumber) ON DELETE CASCADE,	
	CONSTRAINT Enroll_stuId_fk FOREIGN KEY (stuId) REFERENCES Student (stuId)
		ON DELETE CASCADE);
