text: -- Drops the employee_db if it already exists --
  DROP DATABASE IF EXISTS employee_db;
  
  -- Create the database employee_db and specified it for use.
  CREATE DATABASE employee_db;
  
  USE employee_db;
  
  -- Create the tables .
  CREATE TABLE departments (
    id INT AUTO_INCREMENT,
    name VARCHAR(30) NOT NULL,
    PRIMARY KEY(id)
  );
  
  CREATE TABLE roles (
      -- maybe add an increment here??
      id INT PRIMARY KEY NOT NULL,
      title VARCHAR(30) NOT NULL,
      salary DECIMAL(8,3) NOT NULL,
      department_id INT NOT NULL
  );
  
  CREATE TABLE employees (
        id INT AUTO_INCREMENT, 
      first_name VARCHAR(30) NOT NULL, 
      last_name VARCHAR(30) NOT NULL, 
      role_id INT NOT NULL, 
      manager_id INT,
      PRIMARY KEY(id),
  
      FOREIGN KEY(role_id),
      REFERENCES role(id),
  
      FOREIGN KEY(manager_id),
      REFERENCES employee(id)
  );
  