text: DROP DATABASE IF EXISTS employee_db;
  CREATE DATABASE employee_db;
  
  USE employee_db;
  
  CREATE TABLE department (
      id INT NOT NULL AUTO_INCREMENT PRIMARY KEY,
      name VARCHAR(30) NOT NULL
  );
  
  CREATE TABLE roles (
      id INT NOT NULL AUTO_INCREMENT PRIMARY KEY,
      title VARCHAR(30) NOT NULL,
      salary DECIMAL(20,2) NULL,
      department_id INT NOT NULL,
      FOREIGN KEY (department_id)
          REFERENCES department(id)
          ON UPDATE CASCADE
  );
  
  CREATE TABLE employee (
      id INT NOT NULL AUTO_INCREMENT PRIMARY KEY,
      first_name VARCHAR(30) NOT NULL,
      last_name VARCHAR(30) NOT NULL,
      roles_id INT NOT NULL,
      manager_id INT NULL,
      FOREIGN KEY (roles_id)
          REFERENCES roles(id)
          ON UPDATE CASCADE,
      FOREIGN KEY (manager_id)
          REFERENCES employee(id)
          ON UPDATE CASCADE
  
  );