DBMB lab

CREATE TABLE  DEPARTMENT
   (
DEPT_NAME VARCHAR2(15),
	BUILDING VARCHAR2(20) NOT NULL ENABLE,
	BUDGET NUMBER(10,6),
	 PRIMARY KEY ("DEPT_NAME") ENABLE
   ) ;
insert into department  values('cse','B',25)

CREATE TABLE  "INSTRUCTOR"
   (	"ID" CHAR(5),
	"NAME" VARCHAR2(20) NOT NULL ENABLE,
	"DEPT_NAME" VARCHAR2(15),
	"SALARY" NUMBER(5,6),
	 PRIMARY KEY ("ID") ENABLE
   ) ;

insert into instructor values('122', 'tuhin', 'cse', 0)

create table classroom(
building varchar(5),
room_no varchar(10),
capacity number(20),
primary key(building, room_no))
insert into classroom  values('B','1005',25)


create table course(
course_id varchar(5),
title varchar(10),
dept_name varchar(20),
credit number(2,2) check (credit>0),
primary key(course_id),
foreign key(dept_name) references department (dept_name))

create table prereq(
course_id varchar(5),
prereq_id varchar(10),
primary key(course_id,prereq_id),
foreign key(course_id) references course (course_id) on delete cascade,
foreign key(prereq_id) references course (course_id) on delete set null
)