text: DROP DATABASE IF EXISTS employee_db;
  CREATE DATABASE employee_db;
  USE employee_db;
  
  CREATE TABLE department (
  id INT NOT NULL AUTO_INCREMENT,
  dept_name VARCHAR(30),
  PRIMARY KEY(id)
  );
  
  CREATE TABLE emp_role (
  id INT NOT NULL AUTO_INCREMENT,
  title VARCHAR(30),
  salary DECIMAL,
  department_id INT,
  PRIMARY KEY(id)
  );
  
  CREATE TABLE employee (
  id INT NOT NULL AUTO_INCREMENT,
  first_name VARCHAR(30),
  last_name VARCHAR(30),
  role_id INT,
  manager_id INT,
  PRIMARY KEY(id)
  );
  
  SELECT employee.first_name, employee.last_name, emp_role.title, emp_role.salary, department.dept_name, manager.first_name AS manager_firstname, manager.last_name AS manager_lastname FROM employee
  LEFT JOIN emp_role 
  ON employee.role_id = emp_role.id
  LEFT JOIN department
  ON emp_role.department_id = department.id
  LEFT JOIN employee manager 
  ON employee.manager_id = manager.id;
  
  SELECT emp_role.title, emp_role.salary, department.dept_name FROM emp_role
  LEFT JOIN department
  ON emp_role.department_id = department.id;
  
  INSERT INTO department (dept_name)
  VALUES ("Human Resources"), ("Janitorial"), ("Engineering");
  
  INSERT INTO emp_role (title, salary, department_id)
  VALUES ("Manager", "90000", 1), ("Janitor", "150000", 2), ("Engineer", "75000", 3);
  
  INSERT INTO employee (first_name, last_name, role_id, manager_id)
  VALUES ("Jack", "Jones", 1, 2), ("Mister", "Cat", 2, 1), ("Katya", "Zamo", 3, 1),
  ("Trixie", "Mattell", 3, 2), ("Jinkx", "Monsoon", 3, 1), ("Lady", "Gaga", 2, 3);