CREATE TABLE group_reviews (
	review_id serial PRIMARY KEY,


	group_id INT REFERENCES groups (group_id) NOT NULL,
	subject_id INT REFERENCES subjects (id) NOT NULL,
        posting_date DATE NOT NULL
);


CREATE TABLE student_subjects (
	id serial PRIMARY KEY,
	student_id INT REFERENCES students (student_id)
	NOT NULL,
	subject_id INT REFERENCES subjects (id)
	NOT NULL
);