text: -- drop database if existing the create new database
  DROP DATABASE IF EXISTS employee_tracker;
  CREATE DATABASE employee_tracker;
  
  USE employee_tracker;
  
  -- creates department table
  CREATE TABLE department (
      id INT PRIMARY KEY AUTO_INCREMENT,
      name VARCHAR(30) NOT NULL
  );
  
  -- creates role table
  CREATE TABLE role (
      id INT PRIMARY KEY AUTO_INCREMENT,
      title  VARCHAR(30) NOT NULL,
      salary DECIMAL NOT NULL,
      department_id INT,
      FOREIGN KEY (department_id) REFERENCES department(id) ON DELETE SET NULL
  );
  
  -- creates employee table
  CREATE TABLE employee (
      id INT NOT NULL PRIMARY KEY AUTO_INCREMENT,
      first_name VARCHAR(30) NOT NULL,
      last_name VARCHAR(30) NOT NULL,
      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
  );
  
  -- Prevents ERROR 1452 (23000): Cannot add or update a child row: a foreign key constraint fails due to no REFERENCE id exists on initial table creation
  -- SET FOREIGN_KEY_CHECKS=0;