ALTER TABLE users RENAME TO students;

CREATE TABLE courses (
  dept VARCHAR(4),
  number CHAR(4),
  title VARCHAR(255),
  PRIMARY KEY (dept,number)
) ENGINE=InnoDB;

CREATE TABLE grades ( 
  email VARCHAR(40), 
  dept VARCHAR(4), 
  course CHAR(4), 
  year YEAR(4), 
  semester VARCHAR(10), 
  grade VARCHAR(2), 
  PRIMARY KEY (email,dept,course,year,semester), 
  FOREIGN KEY (email) REFERENCES students(email) ON DELETE CASCADE, 
  FOREIGN KEY (dept,course) REFERENCES courses(dept,number) ON DELETE CASCADE 
) ENGINE = InnoDB;