text: -- create table to save favorite course of student
  create table favoritecourse (
  	favoritecourseid bigserial NOT NULL,
  	studentid bigint not null,
  	courseid bigint not null,
  	CONSTRAINT favoritecourse_pkey PRIMARY KEY (favoritecourseid),
  	CONSTRAINT favoritecourse_studentid_foreign FOREIGN KEY (studentid) REFERENCES "user"(userid),
  	CONSTRAINT favoritecourse_courseid_foreign FOREIGN KEY (courseid) REFERENCES course(courseid)
  );
  
  alter table student_course add column status varchar(20) not null default 'OPEN';
  
  alter table review add column userid bigint not null references "user"(userid);
  
  alter table review alter column rating type float;
  
  alter table course add column disabled boolean not null default false;
  
  alter table course drop column disabled;
  
  alter table course add column publish boolean not null default true;
  
  alter table coursevideo add column title text;
  
  alter table coursevideo add column description text;