text: DROP DATABASE IF EXISTS emp_trackerDB;
  
  CREATE DATABASE emp_trackerDB;
  
  USE emp_trackerDB;
  
  CREATE TABLE department (
  	id INT AUTO_INCREMENT NOT NULL,
      name VARCHAR(30) NOT NULL,
      PRIMARY KEY (id)
  );
  
  CREATE TABLE roles (
  	id INT AUTO_INCREMENT NOT NULL,
      title VARCHAR(30) NOT NULL,
      salary DECIMAL,
      department_id INT,
      FOREIGN KEY (department_id) REFERENCES department(id),
  	PRIMARY KEY (id)
  );
  
  CREATE TABLE managers(
    id INT AUTO_INCREMENT NOT NULL,
    first_name VARCHAR(30),
    last_name VARCHAR(30),
    PRIMARY KEY (id)
  );
  
  CREATE TABLE employees (
  	id INT AUTO_INCREMENT NOT NULL,
      first_name VARCHAR(30),
      last_name VARCHAR(30),
      role_id INT NOT NULL,
      department_id INT NOT NULL,
      manager_id INT,
  	PRIMARY KEY (id),
      FOREIGN KEY (role_id) REFERENCES roles(id),
      FOREIGN KEY (manager_id) REFERENCES managers(id),
      FOREIGN KEY (department_id) REFERENCES department(id)
  );
  