text: -- At first create the tables bind and category that have no foreign keys
  CREATE TABLE bind(
      bind_id INT PRIMARY KEY,
      bind_type VARCHAR(15)
  );
  
  CREATE TABLE category(
      cat_id INT PRIMARY KEY,
      cat_name VARCHAR(15)
  );
  
  -- Then create employee table that has a foreing key that points back to itself
  CREATE TABLE employee(
      emp_id INT PRIMARY KEY,
      first_name VARCHAR(20),
      last_name VARCHAR(20),
      gender VARCHAR(1),
      start_date DATE,
      super_id INT
  );
  
  ALTER TABLE employee
  ADD FOREIGN KEY(super_id) REFERENCES employee(emp_id) ON DELETE SET NULL;
  
  
  
  -- Now create all tables who have foreing keys that point to already existing tables
  CREATE TABLE room(
      room_id INT PRIMARY KEY,
      room_name VARCHAR(15),
      flooor VARCHAR(1),
      mgr_id INT,
      FOREIGN KEY(mgr_id) REFERENCES employee(emp_id) ON DELETE SET NULL
  );
  DESCRIBE room;
  
  CREATE TABLE book(
      book_id INT PRIMARY KEY,
      title VARCHAR(30),
      author VARCHAR(30),
      publ_year INT,
      lang VARCHAR(15),
      cat_id INT,
      bind_id INT,
      room_id INT,
      FOREIGN KEY (cat_id) REFERENCES category(cat_id) ON DELETE SET NULL,
      FOREIGN KEY (bind_id) REFERENCES bind(bind_id) ON DELETE SET NULL,
      FOREIGN KEY (room_id) REFERENCES room(room_id) ON DELETE SET NULL
  );
  describe book;
  
  
  CREATE TABLE student(
      std_id INT PRIMARY KEY,
      first_name VARCHAR(20),
      last_name VARCHAR(20),
      gender VARCHAR(1),
      dept VARCHAR(20),
      semester INT,
      phone VARCHAR(12),
      assist_id INT,
      FOREIGN KEY (assist_id) REFERENCES employee(emp_id) ON DELETE SET NULL
  );
  
  
  CREATE TABLE borrows(
      std_id INT, 
      book_id INT,
      start_day DATE,
      end_day DATE,
      statous VARCHAR(12),
      FOREIGN KEY (std_id) REFERENCES student(std_id) ON DELETE CASCADE,
      FOREIGN KEY (book_id) REFERENCES book(book_id) ON DELETE CASCADE,
      PRIMARY KEY(std_id,book_id)
  );
  
  CREATE TABLE supplier(
      cat_id INT,  
      supplier_name VARCHAR(40),
      sales INT,
      FOREIGN KEY (cat_id) REFERENCES category(cat_id) ON DELETE CASCADE,
      PRIMARY KEY(cat_id,supplier_name)
  );
  
  