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