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