text: DROP DATABASE IF EXISTS db;
  CREATE DATABASE db;
  USE db;
  
  CREATE TABLE department (
      id INTEGER AUTO_INCREMENT PRIMARY KEY,
      department_name VARCHAR(30) NOT NULL
  );
  
  CREATE TABLE role (
      id INTEGER AUTO_INCREMENT PRIMARY KEY,
      title VARCHAR(30) NOT NULL,
      salary DECIMAL NOT NULL,
      department_id INTEGER
  );
  
  CREATE Table employee (
      id INTEGER AUTO_INCREMENT PRIMARY KEY,
      first_name VARCHAR(30) NOT NULL,
      last_name VARCHAR(30) NOT NULL,
      role_id INTEGER,
      manager_id INTEGER
  );