text: DROP DATABASE IF EXISTS employees_tracker_db;
  
  CREATE DATABASE employees_tracker_db;
  
  USE employees_tracker_db;
  
  CREATE TABLE department (
    id INT NOT NULL AUTO_INCREMENT,
    name VARCHAR(30),
    PRIMARY KEY (id)
  );
  
  CREATE TABLE role (
    id INT NOT NULL AUTO_INCREMENT,
    title VARCHAR(30),
    salary DECIMAL,
    department_id INT,
    PRIMARY KEY (id),
    CONSTRAINT fk_department FOREIGN KEY (department_id) REFERENCES department(id) ON DELETE CASCADE
  );
  
  CREATE TABLE employee (
    id INT NOT NULL AUTO_INCREMENT,
    first_name VARCHAR(30),
    last_name VARCHAR(30),
    role_id INT NOT NULL,
    manager_id INT,
    PRIMARY KEY (id),
    CONSTRAINT fk_role FOREIGN KEY (role_id) REFERENCES role(id) ON DELETE CASCADE,
    CONSTRAINT fk_manager FOREIGN KEY (manager_id) REFERENCES employee(id) ON DELETE SET NULL
  );
  