text: DROP TABLE IF EXISTS department;
  DROP TABLE IF EXISTS employee_role;
  DROP TABLE IF EXISTS employee;
  
  CREATE TABLE department (
      id INTEGER AUTO_INCREMENT PRIMARY KEY,
      branch VARCHAR(30) NOT NULL
  );
  
  CREATE TABLE employee_role (
      id INTEGER AUTO_INCREMENT PRIMARY KEY,
      title VARCHAR(30) NOT NULL,
      salary DECIMAL NOT NULL,
      dept_id INTEGER,
      CONSTRAINT fk_department FOREIGN KEY (dept_id) REFERENCES department(id) ON DELETE CASCADE
  );   
  
  CREATE TABLE employee (
      id INTEGER AUTO_INCREMENT PRIMARY KEY,
      first_name VARCHAR(30) NOT NULL,
      last_name VARCHAR(30) NOT NULL,
      role_id INTEGER,
      manager_id INTEGER, 
      CONSTRAINT fk_role FOREIGN KEY (role_id) REFERENCES employee_role(id) ON DELETE SET NULL
     
      
  
  );