text: CREATE DATABASE Employee_Tracker;
  
  USE Employee_Tracker;
  
  CREATE TABLE Department (
  id INTEGER AUTO_INCREMENT NOT NULL,
  name VARCHAR(30) NOT NULL,
  PRIMARY KEY(id)
  );
  
  CREATE TABLE Role (
  id INTEGER AUTO_INCREMENT NOT NULL,
  Title VARCHAR(30) NOT NULL,
  Salary DECIMAL  NOT NULL,
  Department_id INTEGER NOT NULL,
  PRIMARY KEY(id)
  );
  
  CREATE TABLE Employee (
  id INTEGER AUTO_INCREMENT NOT NULL,
  First_name VARCHAR(30) NOT NULL,
  Last_name VARCHAR(30) NOT NULL,
  Role_id INTEGER NOT NULL,
  Manager_id INTEGER,
  PRIMARY KEY(id)
  );
  
  ALTER TABLE Employee
  ALTER Manager_id SET DEFAULT NULL;
  
  SELECT name AS "Department" FROM Department;