text: --CREATE DATABASE employee_db;
  
  USE employees_db;
  
  CREATE TABLE department (
   id INT AUTO_INCREMENT NOT NULL,
   name VARCHAR(30),
   PRIMARY KEY (id)
  );
  
  CREATE TABLE role (
   id INT AUTO_INCREMENT NOT NULL,
   title VARCHAR(30),
  salary DECIMAL,
  department_id  INT,
  PRIMARY KEY (id),
  FOREIGN KEY (department_id) REFERENCES department(id) ON DELETE CASCADE
  );
  
  CREATE TABLE employee(
   id INT AUTO_INCREMENT NOT NULL,
   first_name VARCHAR(30),
   last_name VARCHAR(30),
   role_id INT NOT NULL,
   manager_id INT,
   PRIMARY KEY (id),
   FOREIGN KEY (role_id) REFERENCES role(id) ON DELETE CASCADE,
   FOREIGN KEY (manager_id) REFERENCES employee(id) ON DELETE CASCADE
  );
  
  INSERT INTO department (name) VALUES ("Research");
  INSERT INTO department (name) VALUES ("Acounting");
  INSERT INTO department (name) VALUES ("Finance");
  
  INSERT INTO role (title, salary, department_id) VALUES ("Research Analyst", 80000, 1);
  INSERT INTO role (title, salary, department_id) VALUES ("Manager", 10000, 2);
  INSERT INTO role (title, salary, department_id) VALUES ("Finance Analyst",20000 ,);
  
  INSERT INTO employee (first_name, last_name, role_id, manager_id) VALUES ("Andrew", "K", 1,);
  INSERT INTO employee (first_name, last_name, role_id) VALUES ("Ross", "S", 2);
  INSERT INTO employee (first_name, last_name, role_id) VALUES ("Al", "T", 3);