text: DROP DATABASE employee_db;
  CREATE DATABASE IF NOT EXISTS employee_db;
  
  USE employee_db;
  
  CREATE TABLE employee (
      id INT NOT NULL 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 (manager_id) REFERENCES employee(id)
  );
  
  
  CREATE TABLE role (
      id INT NOT NULL AUTO_INCREMENT,
      title VARCHAR(30) NOT NULL,
      salary DEC(20,2) NOT NULL,
      department_id VARCHAR(20) NOT NULL,
      PRIMARY KEY (id)
  );
  
  CREATE TABLE department (
      id INT NOT NULL AUTO_INCREMENT,
      name VARCHAR(30) NOT NULL,
      PRIMARY KEY (id)
  );
  
  
  
  
  
  