text: DROP DATABASE IF EXISTS department_db;
  CREATE DATABASE department_db;
  USE department_db;
  
  CREATE TABLE department (
      id INTEGER AUTO_INCREMENT PRIMARY KEY,
      name VARCHAR(30) NOT NULL
  );
  /* creating role table, will give job title and salary along with the department
  employee belongs to*/
  CREATE TABLE role (
      id INTEGER AUTO_INCREMENT PRIMARY KEY,
      title VARCHAR(30) NOT NULL,
      salary DECIMAL(9,2),
      department_id INTEGER,
      CONSTRAINT fk_department FOREIGN KEY (department_id) REFERENCES department(id) ON DELETE SET NULL
  );
  /* creating table section, first name/last name role of employee and who
  are their assigned manager. manager will be set to NULL*/
  CREATE TABLE employee (
      id INTEGER AUTO_INCREMENT PRIMARY KEY,
      first_name VARCHAR(30) NOT NULL,
      last_name VARCHAR(30) NOT NULL,
      role_id INTEGER,
      manager_id INTEGER,
      CONSTRAINT fk_role FOREIGN KEY (role_id) REFERENCES role(id) ON DELETE SET NULL
  );