text: -- Create a database for holding employee information --
  DROP DATABASE IF EXISTS employee_db;
  CREATE DATABASE employee_db;
  
  USE employee_db;
  
  -- Table for departments --
  CREATE TABLE department (
    id INT NOT NULL AUTO_INCREMENT,
    name VARCHAR(30),
    PRIMARY KEY (id)
  );
  
  -- Table for roles for employees --
  CREATE TABLE role (
    id INT NOT NULL AUTO_INCREMENT,
    title VARCHAR(30),
    salary DECIMAL,
    department_id INT,
    FOREIGN KEY (department_id) REFERENCES department(id) ON DELETE SET NULL,
    PRIMARY KEY (id)
  );
  
  -- Table for employees --
  CREATE TABLE employee (
    id INT NOT NULL AUTO_INCREMENT,
    first_name VARCHAR(30),
    last_name VARCHAR(30),
    role_id INT,
    manager_id INT,
    FOREIGN KEY (role_id) REFERENCES role(id) ON DELETE SET NULL,
    FOREIGN KEY (manager_id) REFERENCES employee(id) ON DELETE SET NULL,
    PRIMARY KEY (id)
  );