text: DROP DATABASE IF EXISTS corporateStructure_DB;
  CREATE DATABASE corporateStructure_DB;
  USE corporateStructure_DB;
  
  CREATE TABLE department (
      id INT NOT NULL AUTO_INCREMENT,
      name VARCHAR(30) NOT NULL,
      PRIMARY KEY (id)
  );
  
  CREATE TABLE role (
      id INT NOT NULL AUTO_INCREMENT,
      title VARCHAR(30) NOT NULL,
      salary DECIMAL (10,2) NOT NULL,
      department_id INT,
      PRIMARY KEY (id),
      FOREiGN KEY (department_id) REFERENCES department(id)
  );
  
  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 role(id) 
  );