CREATE TABLE towns (
id INT PRIMARY KEY AUTO_INCREMENT,
name VARCHAR(45) NOT NULL
);

CREATE TABLE addresses (
id INT PRIMARY KEY AUTO_INCREMENT,
address_text  VARCHAR(100) NOT NULL,
town_id INT  NOT NULL
);

CREATE TABLE departments (
id INT PRIMARY KEY AUTO_INCREMENT,
name  VARCHAR(45) NOT NULL
);

CREATE TABLE employees (
id INT PRIMARY KEY AUTO_INCREMENT,
first_name  VARCHAR(45) NOT NULL,
middle_name  VARCHAR(45) ,
last_name  VARCHAR(45) NOT NULL,
job_title  VARCHAR(45) NOT NULL,
department_id INT  NOT NULL,
hire_date DATE  NOT NULL,
salary INT  NOT NULL,
address_id  INT NOT NULL
);

ALTER TABLE addresses
ADD CONSTRAINT fk_address_town FOREIGN KEY (`town_id`)
REFERENCES towns(id);

ALTER TABLE employees
ADD CONSTRAINT fk_employees_departments FOREIGN KEY (`department_id`)
REFERENCES departments (`id`),
ADD CONSTRAINT fk_employees_address FOREIGN KEY (`address_id`)
REFERENCES addresses (`id`) ;