text: DROP DATABASE IF EXISTS employee_db;
  CREATE DATABASE employee_db;
  
  USE employee_db;
  
  CREATE TABLE department (
    id INT NOT NULL AUTO_INCREMENT,
    name VARCHAR(30) NOT NULL,
    PRIMARY KEY (id)
    );
  
  CREATE TABLE role(
  id INT(10) AUTO_INCREMENT NOT NULL ,
  title VARCHAR(500) NOT NULL,
  salary decimal (8,0) NOT NULL,
  department_id INT (10),
  PRIMARY KEY (id),
  FOREIGN KEY (department_id) REFERENCES department(id)
  
  );
  CREATE TABLE employee (
  id INT NOT NULL AUTO_INCREMENT,
  first_name VARCHAR(30) NOT NULL,
  last_name VARCHAR(30) NOT NULL,
  role_id INT(10),
  manager_id INT,
  PRIMARY KEY (id),
  FOREIGN KEY (role_id) REFERENCES department(id),
  FOREIGN KEY (manager_id) REFERENCES department(id)
  );
  
  SELECT * FROM department;
  SELECT * FROM roles;
  SELECT * FROM employee;
  